Presentación sobre la evaluación del nódulo tiroideo, que abordaje se debe llebar a cabo al encontrar uno por exploración física y por estudios de imagen.
Diagnóstico, tratamiento, pronóstico y ca de tiroides.
Dermis, Hipodermis y receptores sensoriales de la piel-Histología.pptx
Evaluación Del Nódulo Tiroideo y Cáncer De Tiroides
1. INSTITUTO MEXICANO DEL SEGURO SOCIAL
UMAE 71
TORREÓN, COAHUILA
EVALUACIÓN DEL NÓDULO TIROIDEO
CÁNCER DE TIROIDES
Edwin Daniel Maldonado Domínguez R2 Medicina Interna
Asesor: Joaquín Sánchez Sánchez R3 Medicina Interna
2.
3. o Problema clínico frecuente
o Prevalencia de 5% en mujeres y 1% en hombres
o Por imagen (ultrasonido) hasta en 19-68% de la población
o 7-15% de los pacientes van a desarrollar cáncer
Haugen, B. Alexander, E. et al. 2015 American Thyroid Association Management Guidelines for Adult
Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid, 26(1), 1-133.
4. Aparecen en
personas
eutiroideas
Síntomas
compresivos o
problemas
cosméticos
El mayor reto
es descartar
malignidad
Siempre realizar
US
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
5. Condiciones asociadas con incremento en el riesgo
de que el nódulo tiroideo sea maligno
Historia de CA de tiroides en familiar de primer grado
Historia de exposición a radiación en la infancia o adolescencia
Diagnóstico previo de CA de tiroides
Sexo masculino
Historia personal o familiar de neoplasia endocrina múltiple tipo 2
Niveles de calcitonina mayor a 50 – 100 pg/ml
Vivir cerca de zonas con alta radiación
Burman, K, Wartofsky, L. Thyroid Nodules. N Engl J Med 2015;373:2347-56.
6. Asintomáticos
Masa o cuerpo
extraño en
faringe
Disfagia y
odinofagia
Disfonía Disnea Dolor
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
7. Lossíntomasdependendela
localización
Nódulos mayores a 3 cm: masa o tumoración
Disfagia por compresión extrínseca
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
8. Crecimiento rápido
sugiere cáncer
(o sangrado)
Ronquera por invasión
del nervio laríngeo
recurrente
Historia familiar de
cáncer de tiroides,
mama y colon
(síndrome de Cowden)
Historia de familiar con
cáncer papilar de
tiroides
Burman, K, Wartofsky, L. Thyroid Nodules. N Engl J Med 2015;373:2347-56.
9. o Inspección
o Palpación
o Frecuentemente normal
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
11. DIAGNÓSTICOS DIFERENCIALES
Condiciones congénitas (higroma quístico, quiste del
conducto tirogloso)
Infección / Inflamación (linfadenopatías, sialoadenitis,
abscesos, tuberculosis)
Trauma
Nódulo tiroideo
Malignidad
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
12. Niveles de TSH y
hormonas
tiroideas
En todos los
pacientes primer
estudio solicitado
Descarta nódulos
hiper funcionantes
(5%)
Tiroxina libre y
anticuerpos anti
peroxidasa son
útiles
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
13. Tiroglobulina
• No se recomienda de rutina para la evaluación
de nódulo tiroideo
• Puede elevarse en procesos benignos como
tiroiditis
• Poca especificidad para diagnóstico de cáncer
de tiroides
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
14. Calcitonina
• Producido por células parafoliculares C
• Marcador de cáncer medular de tiroides
• No se recomienda de rutina para
abordaje de nódulo tiroideo
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
15. Primera
herramienta que
debemos utilizar
Se solicita cuando la
tiroides se palpa
anormal o hay un
hallazgo de un nódulo
Nos indica cuando
solicitar biopsia por
aspiración con aguja
fina
El US debe describir el parénquima, localización y
características del nódulo y ganglios cervicales
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
16. Composición sólida
Hipoecogenicidad (nódulo más oscuro que parénquima)
Márgenes irregulares
Microcalcificaciones
Nódulo rodeado por calcificaciones
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
17. Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
Nódulos quísticos
Espongiformes (más de la mitad del nódulo formado por
pequeños quistes)
Nódulos sólidos no calcificados
Nódulos isoecoicos o hiperecoicos
Menos del 2%
riesgo de
malignidad
Menos del 5-
10% riesgo de
malignidad
18.
19.
20. Bajo riesgo
Quístico
Halo regular
Isoecoico
Riesgo
moderado
Hipoecoico
Vascularización
intranodular
Macro
calcificacipnes
Riesgo elevado
Hipoecogenicidad marcada
Márgenes microlobulados
Microcalcificaciones
Más altos de anchos
Adenopatías extra tiroideas
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
21. Biopsia por aspiración con aguja fina
Simple, seguro, confiable
Si el nódulo no es palpable puede ser
guiada por US
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
22. Nódulos con
diámetro <5 deben
ser monitorizados
Nódulos de 5-10
mm con datos
sugestivos de
malignidad por US
Lesiones
subcapsulares y
paratraqueales
Nódulos linfáticos
sospechosos
Cáncer de tiroides
en la familia
Clínica sospechosa
como disfonía
Lesiones de alto
riesgo mayores de
10 mm
Lesiones de
moderado riesgo
mayores de 20 mm
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
23. CATEGORÍA RIESGO DE
MALIGNIDAD %
TRATAMIENTO HABITUAL
CATEGORIA 1: No diagnóstico
Fluidos de quistes, acelular, sangre
0-5 Repetir biopsia guiada por
ultrasonido
CATEGORÍA 2: Benigno
Nódulo folicular, tiroiditis crónica linfocítica, granulomatosis
0-3 Seguimiento clínico y por imagen
CATEGORÍA 3: Atipia
Atipia focal nuclear, patrón microfolicular en un espécimen
hipocelular
10-30 Repetir biopsia, test molecular o
lobectomía
CATEGORÍA 4: Neoplasia folicular o sospecha
Células foliculares superpuestas
25-40 Test molecular, lobectomía
CATEGORÍA 5: Sospecha de malignidad
Sospecha de cáncer de tiroides papilar, medular, metastásico
50-75 Tiroidectomía o lobectomía
CATEGORÍA 6: Malignidad
Cáncer de tiroides papilar, carcinoma pobremente diferenciado,
cáncer medular de tiroides, carcinoma indiferenciado
97-99 Tiroidectomía total
El sistema de BETHESDA para reportar la citología de tiroides
24. Burman, K,
Wartofsky, L. Thyroid
Nodules. N Engl J
Med 2015;373:2347-
56.
Carcinoma papilar
Carcinoma papilar
Adenoma
HiperplasiaBenigno
25. Categorías 3-4
representan el 20-
30% de las biopsias
Se trata de evitar
cirugía
La mayoría de los
nódulos son
benignos
Cuando se
identifica cáncer es
en etapas
tempranas
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
26. Se utilizan para nódulos tiroideos con resultados de citología
indeterminados
Mutaciones ocurren principalmente en genes que codifican para
proteínas quinasas activadas por mitógenos (MAPK)
Vía que regula proliferación celular y diferenciación
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
27. Gen BRAF
Ca papilar (40%)
Pobremente
diferenciados (33%)
Ca anaplásico (45%)
Gen RAS
Ca papilar (13%)
Ca folicular (40-
50%)
TERT
Ca papilar (10%)
Ca anaplásico (70%)
TP53
Ca papilar (1%)
Ca anaplásico (70%)
Algunas mutaciones son:
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
28. 1er
Método:
Análisis de
mutaciones y
genes de
expresión
Material
obtenido por
la BAAF
Se aísla el DNA
de células
foliculares y se
buscan las
posibles
mutaciones
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
29. 2do
Método:
Análisis de
expresión de
genes
Analiza la
expresión de
genes
específicos en
un panel con
142 genes
Los nódulos
se clasifican
como
benignos o
sospechosos
de malignidad
Durante, C. Grani, G. Lamartina, L. The Diagnosis and Management of Thyroid Nodules. A Review. JAMA.
2018; 319(9); 914-924.
30. o ULTRASONIDO
o SI SON MAYORES DE 1 CM BIOPSIA POR ASPIRADO CON
AGUJA FINA SI TIENEN DATOS DE POSIBLE MALIGNIDAD
o SI MIDEN MÁS DE 1.5 CM BIOPSIA POR ASPIRADO CON AGUJA
FINA CON POCA SOSPECHA DE MALIGNIDAD
o NÓDULOS MAYORES DE 2 CM SIEMPRE BAAF
De acuerdo a las guías de la asociación Americana de tiroides:
Burman, K, Wartofsky, L. Thyroid Nodules. N Engl J Med 2015;373:2347-56.
31. o ADENOPATÍAS CERVICALES SOSPECHOSAS DEBEN SER
BIOPSIADAS
o SI ES UNA TIROIDES MULTINÓDULAR CADA NÓDULO MAYOR
DE 1CM TIENE RIESGO DE MALIGNIDAD
o SI DUDA PRUEBAS GENÉTICAS
o SI HAY BAJO RIESGO DE MALIGNIDAD, SEGUIMIENTO
De acuerdo a las guías de la asociación Americana de tiroides:
Burman, K, Wartofsky, L. Thyroid Nodules. N Engl J Med 2015;373:2347-56.
32. Nódulo tiroideo encontrado clínicamente o por imagen
Historia, examen físico, medir TSH, ultrasonido
Niveles elevados o normales de TSH
Niveles disminuidos de TSH
BAAF en nódulos mayores de 1 cm
No diagnóstico
Sospechoso de malignidad
Maligno
Benigno
Atipia o indeterminado
Repetir US con BAAF
Tiroidectomía
Repetir US en 1-2 años
En 6 meses si factores de riesgo
Si aumenta más de 50% de volumen, más de 20% un nódulo
o tiene características sospechosas por US repetir BAAF
Sospecha baja: perfil de expresión genética
Sospecha alta: buscar anormalidades moleculares
Gammagrama tiroideo
Nódulo
funcional
Nódulo no
funcional
Tratar
hipertiroidismo
Burman,K,Wartofsky,L.
ThyroidNodules.NEnglJ
Med2015;373:2347-56.
33. Repetir ultrasonido
Cuando los reportes citológicos son repetidamente negativos
se recomienda biopsia guiada por US
Cirugía para nódulos sólidos hipoecogénicos
BAAF no
diagnóstica
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
34. Repetir ultrasonido y TSH en 12 meses si no hay
nuevos síntomas
Si el primer US es normal se puede repetir en 24 meses
Si el nódulo es benigno por citología pero sospechoso por US se recomienda
repetir la BAAF
Nódulos
benignos
por BAAF
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
35. TRATAMIENTO MÉDICO
• Pacientes jóvenes con nódulos pequeños y THS elevada
valorar suplemento con Yodo
• No se recomienda terapia supresora con LT4 (Levotiroxina)
• Después de lobectomía no se recomienda terapia con LT4 si
niveles de TSH de mantienen dentro del rango normal
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
36. INDICACIONES QUIRÚRGICAS PARA
NÓDULOS BENIGNOS
Síntomas compresivos
No compatibles con benignidad por US a pesar de BAAF
Tratamiento óptimo: lobectomía con resección de istmo si es 1
nódulo o tiroidectomía total si multinodular
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
37. Inyección
percutánea de
etanol
Nódulos benignos
con gran contenido
líquido o quistes
Asegurarse que el
contenido no es
maligno
Última opción en
nódulos compresivos
si no hay otra terapia
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
38. Ablación térmica guiada por imagen de
nódulos benignos
Considerar ablación láser o por radiofrecuencia para el
tratamiento de nódulos tiroideos sólidos complejos
asintomáticos o por fines estéticos
Repetir BAAR antes de procedimiento
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
39. Para nódulos
hiperfuncionantes
Sobretodo cuando
no se puede
realizar cirugía
Se recomienda
BAAF previamente
TERAPIA CON YODO RADIOACTIVO
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
40. Lesiones indeterminadas
Manejo
conservador si
no hay factores
de riesgo
Si hay factores
de riesgo
resección
Tiroidectomía,
resección de
istmo,
lobectomía
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici Endocrinologi Medical
Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update. , Endocr Pract. 2016;22 (Suppl 1)
41. Nódulos
malignos
Carcinoma bien
diferenciado se
recomienda resección
quirúrgica
Carcinoma anaplásico,
metástasis, linfoma:
complementar, buscar
tumor primario Realizar US, BAAF y
laringoscopía
peviamente
Gharib, H. American Association Of Clinical Endocrinologists, American College of Endocrinology and Associazione Medici
Endocrinologi Medical Guidelines For Clinical Practica For The Diagnosis and Management of Thyroid Nodules - 2016 Update.
, Endocr Pract. 2016;22 (Suppl 1)
42.
43. o Neoplasia endocrinológica más frecuente
o Cáncer papilar de tiroides representa el 85%
o De 1975 a 2009 se triplicó la incidencia de ca de
tiroides en USA debido a la detección temprana
o Ca folicular del 2-5%
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-
67.
44. Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-
67.
45. Factores de riesgo
• Factores genéticos (mutación protooncogén RET en carcinomas
medulares)
• Radiación externa
• Exposición a algunos productos químicos como hexaclorobenceno y
dioxinas
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-40.
46. Proteín kinasas y
tirosín kinasas (uno
de sus subgrupos)
Enzimas que
controlan la
proliferación y la
diferenciación celular
Su activación en los
tumores inhibe la
apoptosis y estimula
la angiogénesis
Aparición de nueva
clase de fármacos,
inhibidores de tirosín
kinasa
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-
40.
47. Generalmente se manifiesta como nódulo tiroideo en cuello
y/o crecimiento ganglionar cervical
Adenopatías duras, fijas, de bordes mal definidos y de
crecimiento lento
Disnea, dolor, disfonía
GPC: Diagnóstico y Tratamiento del Tumor Maligno de Tiroides. Disponible en:
www.cenetec.salud.gob.mx/descargas/gpc/CatalogoMaestro/166_GPC_TUMOR_MALIGNO_TIROIDEO/
Grr_tumor_tiroideo.pdf
48. Suele manifestarse
como masa tiroidea o
cervical
Crecimiento rápido,
disfagia, disnea,
disfonía, síndrome de
vena cava superior
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid
Cancer. Am Health Drug Benefits. 2015;8(1):30-40.
49. ESTADIFICACIÓN
o Importante estadificación por imagen para pronóstico
y tratamiento
o 50% de los pacientes con ca diferenciado de tiroides
tendrán involucro de nódulos cervicales
o Se recomienda ultrasonido cervical contralateral en
todos los pacientes para identificar metástasis
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-
40.
50. Se clasifica en 4 estadios (I a IV)
Se basa en el tipo de tumor
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-
40.
51. Cáncer papilar y folicular en pacientes menores de 45 años
Estadio l: Ca papilar se localiza en la glándula tiroides
Estadio ll: Ca papilar que se disemina a distancia
Cáncer papilar y folicular en pacientes mayores de 45 años
Estadio l: Ca papilar que se localiza en la glándula tiroides
Estadio ll: Tumor que mide más de 2 cm pero menos de 4 cm y se limita a la glándula
tiroides
Estadio lll: Tumor que mide más de 4 cm y que está limitado a la tiroides o con mínima
extensión extra tiroidea o nódulos linfáticos positivos pretraqueales o paratraqueales
Estadio lV: Extensión más allá de la cápsula de la tiroides hacia tejidos blandos del
cuello, nódulos cervicales con metástasis o metástasis a distancia como pulmón o hueso
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-
40.
52. Cáncer medular de tiroides
Estadio 0: Enfermedad clínicamente oculta detectada por escrutinio bioquímico
Estadio l: Tumor menor de 2 cm
Estadio ll: Tumor que mide más de 2 cm pero menor de 4 cm sin metástasis o más de 4 cm con mínima
afectación extra tiroidea
Estadio lll: Tumor de cualquier extensión con metástasis pre traqueales o paratraqueales
Estadio lV:
IVA: Enfermedad moderadamente avanzada con o sin metástasis a ganglios linfáticos sin metástasis a
distancia
IVB: Enfermedad muy avanzada con o sin metástasis a ganglios linfáticos pero sin metástasis a distancia
IVC: Metástasis a distancia
Cáncer anaplásico de tiroides
Todos los pacientes se consideran en estadio IV
Nguyen, Q. Diagnosis and Treatment of Patients with Thyroid Cancer. Am Health Drug Benefits. 2015;8(1):30-40.
53. • Además de ser diagnósticos, los marcadores moleculares
pueden llevar a decisiones en base a la terapia
• Se emplean para cáncer avanzado
Pacientes con
mutación BRAF
V600E
Inhibidores de
BRAF como
Vemurafenib y
Dabrafenib
Robert I. Haddad, et. al. Thyroid Carcinoma. JNCCN—Journal of the National Comprehensive Cancer Network 2018. 16(12); 1429-
1440.
54. La mayoría son indolentes
clínicamente
Genoma simple, poco
número de alteraciones
Múltiples tipos de tumores
con mutaciones diferentes
de genes
Estos son genes efectores
codificadores que señalizan
a través de la vía de la
proteína quinasa activada
por mitógeno (MAPK)
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
55. Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
56. Mutación BRAF
• Metástasis a nódulos
linfáticos
• Recurrencia posterior a
tiroidectomía
• Pobre respuesta a terapia
con yodo radioactivo
Mutación RAS
• Se asocia con la variante
folicular del carcinoma
papilar de tiroides
• Invasión vascular
• Rara vez afectan ganglios
linfáticos
• Buena respuesta a terapia
con yodo radioactivo
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
57. Representa del 2 al
5% del cáncer de
tiroides
Se asocian con
mutaciones de RAS o
del oncogen de fusión
PAX8-PPARG
El pronóstico depende
del tamaño del tumor,
edad, y grado de
invasión vascular
Carcinoma de células
de Hürthle: metastasis
a pulmón y hueso
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
FACTOR DE
RIESGO:
Exposición a
radiación
ionizante
58. IDENTIFICA
LESIONES DE
ALTO RIESGO
CARCINOMA
PAPILAR DE
TIROIDES
MENOR DE 1
CM
PRIMERA
EVALUACIÓN
ANTE
NÓDULO
TIROIDEO
PUEDE ESTAR
PRESENTE
HASTA EN EL
30% DE LA
POBLACIÓN
ULTRASONIDO
Fagin, J. Wells, S. Biologic and
Clinical Perspectives on Thyroid
Cancer. N Engl J Med 2016;375:1054-
67.
60. Tiroidectomía sin resección
de ganglios cervicales
centrales:
Ca no invasivo
Estadio T1 (menos de 2 cm)
Estadio T2 (más de 2 cm pero menos
de 4cm)
La mayoría de los CA foliculares
Tiroidectomía total con
resección de ganglios
cervicales
Tumores mayores de 4 cm
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
61. Emplea la propiedad de las células foliculares de transportar e incorporar yodo dentro
de la Tiroglobulina, propiedad que conservan algunos tipos de neoplasias tiroideas
No se recomienda para neoplasias de bajo riesgo debido a que la mortalidad es baja y
no mejora el pronóstico del paciente
Se emplea en pacientes con niveles elevados de Tiroglobulina
después de cirugía y que persiste la enfermedad estructural
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer.
N Engl J Med 2016;375:1054-67.
62. Cáncer con
mutación del gen
BRAF es
refractario a
terapia con yodo
radioactivo
La expresión de
genes requeridos
para trasporte de
yodo y
metabolismo es
bajo en pacientes
con mutaciones
del gen BRAF
A diferencia de el
cáncer con
mutación del gen
RAS de ca papilar
de tiroides donde
están
preservados
estos genes
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
63. Seguimiento con US
Medición de niveles de tiroglobulina
10% de los pacientes presentan
recurrencias
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
64. o El CA de tiroides es usualmente indolente aunque presente
metástasis
o Terapia sistémica como radioterapia o quimioterapia se
reserva para pacientes con enfermedad metastásica,
progresiva, sintomática o que pone en riesgo estructuras
vitales y que no es candidato a terapia local como resección
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
65. La FDA aprobó 2
inhibidores
multicinasa para
pacientes con
enfermedad
refractaria a yodo
radioactivo
Sorafenib y
Lenvatinib
Se cree que actúan
inhibiendo
angiogénesis debido
a que inhiben al
receptor del factor
de crecimiento
vascular endotelial
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
66. Carcinomas pobremente
diferenciados representan el 6% de
los cánceres de tiroides con media
de supervivencia de 3.2 años
Histologicamente:
Alto rango de mitosis y presencia de
necrosis. Tratamiento con radio y
quimioterapia
Carcinoma anaplásico representa el
1% de los cánceres de tiroides con
media de supervivencia de 6 meses
Refractarios a terapia con yodo
radioactivo, quimioterapia y
radioterapia con beneficio limitado
Carcinoma anaplásico y pobremente diferenciados
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
67. Tratamiento del carcinoma
anaplásico de tiroides
•Cuando es posible debe ser resecado
•Tratamiento con radiación locoregional
•Quimioterapia con taxanes, solos o en combinación
con carboplatino o doxorrubicina
•Tratamiento paliativo para mantener vía aérea libre
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
68. 3-5% de los cánceres
de tiroides
75% de los pacientes
es esporádico
Aparece en la 4ta a la
6ta década de la vida
Puede ser parte del
síndrome de
neoplasia endocrina
múltiple (MEN) tipo 2
Mutación en el gen
RET que codifica un
receptor tirosin
quinasa
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
69. Las células secretan calcitonina y ACE. Sirve como escrutinio para
pacientes que tienen riesgo para ca medular de tiroides así como
enfermedad recurrente o persistente
Ultrasonido e histopatología de nódulos tiroideos a través de BAAF
Si el reporte histopatológico es inconcluso test de inmunohistoquímica para calcitonina en
células del aspirado o medición de calcitonina en el fluido de la BAAF puede ser diagnóstico
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
70. Tratamiento
quirúrgico
Primera elección tanto en
enfermedad esporádica como
hereditaria
Lobectomía, tiroidectomía total
con o sin resección de ganglios
Seguimiento
Cada 6 meses o anualmente
Niveles de calcitonina sérica nos
hablan de persistencia de enfermedad
Si persiste más de 5 años con niveles de
calcitonina indetectables se dice que el
paciente está libre de enfermedad
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
71. TERAPIA SISTÉMICA
•Para pacientes con enfermedad
progresiva o sintomática
•Inhibidores multicinasa Vandetanib y
Cabozantinib
Fagin, J. Wells, S. Biologic and Clinical Perspectives on Thyroid Cancer. N Engl J Med 2016;375:1054-67.
Notas do Editor
Thyroid nodules are a common clinical problem. Epidemiologic studies have shown the prevalence of palpable thyroid nodules to be approximately 5% in women and 1% in men living in iodine-sufficient parts of the world (1,2). In contrast, high-resolution ultrasound (US) can detect thyroid nodules in 19%–68% of randomly selected individuals, with higher frequencies in women and the elderly (3,4). The clinical importance of thyroid nodules rests with the need to exclude thyroid cancer, which occurs in 7%–15% of cases depending on age, sex, radiation exposure history, family history, and other factors (5,6). Differentiated thyroid cancer (DTC), which includes papillary and follicular cancer, comprises the vast majority (>90%) of all thyroid cancers (7). In the United States, approximately 63,000 new cases of thyroid cancer were predicted to be diagnosed in 2014 (8) compared with 37,200 in 2009 when the last ATA guidelines were published. The yearly incidence has nearly tripled from 4.9 per 100,000 in 1975 to 14.3 per 100,000 in 2009 (9). Almost the entire change has been attributed to an increase in the incidence of papillary thyroid cancer (PTC). Moreover, 25% of the new thyroid cancers diagnosed in 1988–1989 were £1 cm compared with 39% of the new thyroid cancer diagnoses in 2008–2009 (9). This tumor shift may be due to the increasing use of neck ultrasonography or other imaging and early diagnosis and treatment (10), trends that are changing the initial treatment and follow-up for many patients with thyroid cancer.
Thyroid nodules are a common finding because they are detected in up to 50 to 60% of healthy people. In most cases, they appear in euthyroid persons and cause neither compressive symptoms nor cosmetic concerns. Accordingly, the main clinical challenge in the treatment of these patients is to rule out malignancy. Most patients with thyroid nodules are asymptomatic, but the absence of symptoms does not rule out malignancy. Thus, clinical and US risk factors for malignant disease should always be reviewed. All patients with a palpable thyroid nodule or clinical risk factors should undergo US examination. Thyroid FNA should always be performed under US guidance because it makes the procedure safer, more reliable, and more accurate. In light of the low clinical risk, nodules <5 mm should always be monitored with US rather than biopsied. FNA should be considered for nodules with a major diameter ≤5-10 mm only when suspicious US signs are present (high US risk thyroid lesions) in
ClinicalEvaluation
Mostpatients are asymptomatic. Symptoms from a thyroid nodule or thyroid enlargement include: globus sensation (sensation of a lump or foreign body in the throat): dysphagia or swallowing complaints (stasis, choking, odynophagia); dyspnea; dysphonia or hoarseness; and pain (due to acute increase of nodule size, a sin case of bleeding into the nodule).
The presence of symptoms from a thyroid nodule depends on its size and location. In particular,a globus sensation is more likely to be associated with a nodule size of more tan 3 cm and a position close to the trachea (isthmic nodules more tan paraisthmic nodules). Swallowing complaints are reported in 67% of the patients with either hypothyroidism or thyroid nodules. However, if attributable to nodular thyroid disease, the lesion is typically located in the left lobe with posterior extension, such that it may cause extrinsic compression of the cervical esophagus.
Focos ecogénicos discretos
No dan sombra por su tramaño
A: Nódulo tiroideo con una forma ovoide, isoecogenicidad y margen bien definido sin calcificaciones.
E: Nódulo con forma redonda, hipoecogenicidad comparado con el parénquima, margen microlobulado, microcalcificaciones con nódulos linfáticos
How to select nodule(s) for US-guided FNA • In the selection of nodules for US-guided fineneedle aspiration (FNA), consider a balance between the risk of a potentially delayed diagnosis and that of superfluous diagnostic procedures or surgery (see Fig. 1) [BEL 4, GRADE C]. • In light of the low clinical risk, nodules with a major diameter <5 mm should be monitored, rather than biopsied, with US, irrespective of their sonographic appearance [BEL 3, GRADE B]. • In nodules with a major diameter 5-10 mm that are associated with suspicious US signs (high US risk thyroid lesions), consider either FNA sampling or watchful waiting on the basis of the clinical setting and patient preference [BEL 3, GRADE B]. Specifically, US-guided FNA is recommended for the following nodules: ¡ Subcapsular or paratracheal lesions ¡ Suspicious lymph nodes or extrathyroid spread ¡ Positive personal or family history of thyroid cancer
¡
Coexisting suspicious clinical like dysphonia) [BEL 2, GRADE A] • FNA is recommended for the following: ¡ High US risk thyroid lesions ≥10 mm ¡ Intermediate US risk thyroid lesions >20 mm ¡ Low US risk thyroid lesions only when >20 mm and increasing in size or associated with a risk history and before thyroid surgery or minimally invasive ablation therapy [BEL 2, GRADE A] • FNA is not recommended for nodules that are functional on scintigraphy (see difference in recommendations for children; Section 8.4.) [BEL 2, GRADE B].
La figura muestra nódulos en 5 diferentes categorias del sistema de Bethesda. FIGURA A: un nódulo benigno. Las células foliculares están espaciadas y tienen una forma pequeña y nuclear. FIGURA B: atipia indeterminada. Algunas células muestran crecimiento nuclear. El paciente se sometió a tiroidectomía
y la biopsia demostró hiperplasia.
FIGURA C: Neoplasia folicular. Las células foliculares tienen tamaño normal pero forman micro foliculos. El resultado de patología fue un adenoma. FIGURA D: nódulo sospechoso de malignidad. Hay hipercelularidad, crecimiento nuclear, hipercromasia e incremento del tamaño del nucleo con respecto al citoplasma. El resultado fue un carcinoma papilar. FIGURA E: un nódulo maligno. Celulas foliculares anormales que contienen niucleos alargados hipercromáticos con pseidoinclusiones nucleares. R
Panel B the relative frequency of pathologic variants of papillary thyroid carcinoma, with their corresponding main driver mutations shown in parentheses (the symbol > indicates more frequent than). RTK denotes receptor tyrosine kinase. Panel C shows the encapsulated follicular variant of papillary thyroid carcinoma without invasion, which until recently represented 17% of all papillary thyroid carcinomas. This cancer has recently been reclassified as a neoplasm of low malignant potential and is now termed “noninvasive follicular thyroid neoplasm with papillarylike nuclear features” (NIFTP). This change will result in a corresponding reduction in the number of patients who are considered to have thyroid cancer. The hematoxylin and eosin–stained section in the inset shows the characteristic histologic appearance of an NIFTP. The encapsulated tumor has a follicular growth pattern and papillary nuclear features, low mitotic rate, and absence of necrosis and capsular or vascular invasion.
After a diagnosis of thyroid cancer, it is important to perform preoperative staging and imaging, because it can alter the patient’s prognosis and treatment course. Up to 50% of patients with differentiated thyroid cancer will have cervical lymph node involvement, despite the primary tumor size.5 Thus, a preoperative neck ultrasound for contralateral lobe and cervical lymph nodes is recommended for all patients undergoing thyroidectomy for malignancy, to help identify possible metastasis; however, neck ultrasounds only identify 50% of the lymph nodes that are found during surgery.5 Lymph node metastasis ca
The American Joint Committee on Cancer (AJCC) has designated thyroid cancer staging by the Tumor, Node, Metastasis (TNM) classification system.8 The AJCC’s TNM classification system is available online (at the AJCC website).8 In addition, thyroid cancer can be stages, using stages I to IV, with the TNM classification system based on the tumor type of thyroid cancer (Table 1).8
In addition to their utility in diagnostics, molecular markers may drive decisions related to targeted therapy for advanced disease. Systemic therapy can be considered for locally recurrent, advanced, and/ or metastatic DTCs that are not surgically resectable.
Although the clinical use of predictive markers is currently limited for advanced thyroid cancers, recent data have shown that the BRAF inhibitors vemurafenib and dabrafenib can be effective treatment options for DTC harboring the BRAF V600E mutation.54–56 Because this mutation is common in papillary thyroid cancers, these therapies may be especially promising for this tumor type. An openlabel nonrandomized phase II trial of 51 patients with BRAF V600E mutation–positive recurrent or metastatic papillary thyroid cancer that was refractory to RAI investigated the safety and efficacy of vemurafenib.56 Of these 51 patients, 26 had never received a VEGFR-targeted therapy (cohort 1) and 25 had previously received this class of therapy (cohort 2). The primary end point, best overall response rate
Most papillary thyroid carcinomas are indolent clinically, consistent with their simple genome, which has few copy-number alterations. Papillary thyroid carcinoma has one of the lowest mutation densities of cancers that have been studied by means of whole-exome sequencing.2 Although formerly thought to be a single entity, papillary thyroid carcinoma encompasses several tumor types that have mutually exclusive mutations of genes encoding effectors that signal through the mitogen-activated protein kinase (MAPK) pathway.3,4
BRAF V600E accounts for 60% of these mutations, followed by RAS (15%) and chromosomal rearrangements that lead to illegitimate expression of the kinase domains of BRAF or of receptor tyrosine kinases, such as RET, NTRK, and ALK (12%). The remaining 13% mostly have no known driver mutations; a subgroup have copy-number abnormalities but no discrete recurrent genetic lesion. The different driver mutations are associated with different histologic variants of papillary thyroid carcinoma (Fig. 1) and confer distinct patterns of gene expression, signaling, and clinical characteristics.4
high frequency of lymph-node metastases and recurrence after thyroidectomy; these carcinomas also have a poor response to radioiodine therapy.5 Their refractoriness to radioiodine appears to be due to the high MAPK-pathway output that is driven by the BRAF V600E oncoprotein, which suppresses the expression of genes required for iodide incorporation.6 RAS-mutated papillary thyroid carcinomas are associated with the follicular variant of papillary thyroid carcinoma. Follicularvariant papillary carcinomas with vascular invasion spread infrequently to regional lymph nodes, retain the expression of iodine-metabolism genes, and are usually radioiodine-avid (Fig. 2).4,7-11 Encapsulated noninvasive follicular variants of papillary thyroid carcinoma have recently been reclassified as a benign entity and renamed as “noninvasive follicular thyroid neoplasms with papillary-like nuclear features,” thereby substantially reducing the number of patients who are considered to have thyroid cancer (Fig. 1).12
Follicular thyroid carcinomas represent 2 to 5% of thyroid cancers.13 Follicular thyroid carcinoma and follicular variants of papillary thyroid carcinoma are associated with mutually exclusive mutations of RAS or of the PAX8–PPARG fusion oncogene.14 The prognosis of patients with these cancers depends on the size of the tumor, the age of the patient, and the degree of angioinvasiveness, which predicts the risk of distant metastases. Hürthle-cell carcinomas, which are classified as a variant of follicular thyroid carcinoma, are genetically distinct.15 Widely invasive Hürthle-cell carcinomas, which are characterized by extensive capsular and vascular invasion, often metastasize to lung and bone and are particularly refractory to radioiodine.
Exposure to ionizing radiation is a risk factor for the development of papillary thyroid carcinoma. After the nuclear-reactor accident in Chernobyl in 1986, there was a sharp increase in the incidence of papillary thyroid carcinomas, primarily affecting very young children in iodidedeficient regions.16 Similar age-dependent trends were seen after the atomic-bomb explosions in Hiroshima and Nagasaki in 1945 and in persons receiving external radiotherapy for benign or malignant conditions of the head and neck. Radiation-induced papillary thyroid carcinomas have a high prevalence of fusion oncogenes, usually arising from intrachromosomal rearrangements that activate RET or, less frequently, the tyrosine kinase receptors encoded by NTRK.17 These translocations are favored by the spatial proximity of the participating genes during interphase in thyroid cells, which probably predisposes them to recombination after radiationinduced DNA damage.18 The disease-specific mortality is low, both among affected persons who have been followed for several decades and among children with sporadic papillary thyroid carcinoma.
Ultrasonography identifies lesions at high risk for cancer and is the best imaging method for the assessment of thyroid nodules. Papillary thyroid carcinomas that are less than 1 cm in the greatest dimension (papillary microcarcinomas) occur in up to 30% of adults in the general population, yet they rarely become clinically significant. Therefore, papillary microcarcinomas need not be biopsied unless there is extrathyroidal invasion, nodal metastases, or arguably, previous exposure to radiation or a family history of thyroid cancer.
Prospective studies of prolonged surveillance show that most papillary microcarcinomas do not progress, and surgery may be avoided or deferred in selected cases.27 Lobectomy or total thyroidectomy is the treatment of choice for primary thyroid cancers that measure 1 to 4 cm in the greatest dimension.28 Thyroidectomy without prophylactic central neck dissection may be appropriate for noninvasive, node-negative papillary thyroid carcinomas of tumor stage T1 (tumor size ≤2 cm in the greatest dimension; intrathyroidal) or T2 (tumor size >2 cm and ≤4 cm; intrathyroidal) and for most follicular thyroid carcinomas. Clinically involved lymph-node compartments should be resected. Total thyroidectomy with resection of involved lymph-node compartments is the recommended treatment for tumors that are larger than 4 cm in the greatest dimension.
Prospective studies of prolonged surveillance show that most papillary microcarcinomas do not progress, and surgery may be avoided or deferred in selected cases.27 Lobectomy or total thyroidectomy is the treatment of choice for primary thyroid cancers that measure 1 to 4 cm in the greatest dimension.28 Thyroidectomy without prophylactic central neck dissection may be appropriate for noninvasive, node-negative papillary thyroid carcinomas of tumor stage T1 (tumor size ≤2 cm in the greatest dimension; intrathyroidal) or T2 (tumor size >2 cm and ≤4 cm; intrathyroidal) and for most follicular thyroid carcinomas. Clinically involved lymph-node compartments should be resected. Total thyroidectomy with resection of involved lymph-node compartments is the recommended treatment for tumors that are larger than 4 cm in the greatest dimension.
Radioiodine therapy leverages the property of thyroid follicular cells to transport and incorporate iodide into thyroglobulin, a feature that is retained in a subgroup of differentiated thyroid carcinomas. Until recently, most patients with differentiated thyroid carcinoma received postoperative radioiodine therapy despite a lack of data from prospective clinical trials to support the practice. Radioiodine therapy is no longer recommended in patients with low-risk thyroid cancers, because the recurrence rate and mortality are low and large retrospective series have not shown improved outcomes.35,36 The data regarding radioiodine therapy in patients with intermediate-risk disease are not compelling; however, the treatment may be useful in a subgroup of patients who have high levels of thyroglobulin after surgery and persistent structural disease. Postoperative therapy with either 30 or 100 mCi (1.1 or 3.7 GBq) of iodine-131 is equally effective in ablating the remnant thyroid, regardless of whether injections of recombinant human thyrotropin or thyroid-hormone withdrawal is used to induce iodide accumulation.37
Mci: milicurio
BRAF-mutated cancers and those that are positive on FDG-PET scans are often refractory to radioiodine.38 The expression of genes that are required for iodine transport and metabolism is low in most BRAF-mutated cancers, whereas they are comparatively preserved in RAS-mutated papillary thyroid carcinomas (Fig. 2).4 Accordingly, Braf V600E suppresses the expression of these genes in mouse models of papillary thyroid carcinoma and inhibits radioiodine uptake and response to radioiodine therapy, which can be partially restored by treatment with rapidly accelerating fibrosarcoma (RAF) or MAPK kinase (MEK) inhibitors.6 A pilot trial of the MEK inhibitor selumetinib in patients with radioiodinerefractory metastatic thyroid cancer showed the restoration of iodide uptake at metastatic sites in 14 of 20 patients. In 8 of the 14 patients, the uptake was sufficient to enable iodine-131 therapy with remarkable clinical responses (Fig. 2).11 Similar results have been shown with the BRAF inhibitor dabrafenib.3
Patients with low-risk or intermediate-risk disease are followed by means of neck ultrasonography and measurements of serum thyroglobulin levels. Antithyroglobulin antibodies, which are present in patients with autoimmune thyroiditis, can interfere with the accuracy of thyroglobulin immunoassays; however, persistent or rising levels of antithyroglobulin antibody also indicate disease activity. Diagnostic radioiodine scans have low sensitivity and are unhelpful in routine surveillance unless there is structural or biochemical evidence of disease. Additional imaging studies, including FDG-PET scans, may help localize disease in patients with rising levels of thyroglobulin or antithyroglobulin antibody. Clinically apparent persistent or recurrent cervical nodal disease is found in approximately 10% of patients with thyroid cancer. Selected cases can be managed expectantly or by means of surgical resection, thermal destruction, or alcohol ablation.40-42
Thyroid cancers are often indolent, even when they have metastasized to distant sites. Most physicians reserve systemic therapy for patients who have metastatic disease that is progressing, symptomatic, or in a location that threatens vital structures and is not amenable to localized therapies. Palliative radiotherapy, either alone or concomitant with low-dose chemotherapy, or local therapies may control disease in patients with unresectable regional or metastatic disease.40,41,43 Treatment with bisphosphonates or anti–receptor activator of nuclear factor-κB (RANK) ligand antibody may benefit patients who have bone metastases, although the efficacy of the compounds has not been tested in prospective trials.44
The Food and Drug Administration (FDA) approved two multikinase inhibitors, sorafenib and lenvatinib, for the treatment of patients with radioiodine-refractory metastatic thyroid cancer on the basis of phase 3, prospective, doubleblind, randomized, placebo-controlled trials that showed longer progression-free survival (Table 1).45,46 Although the two drugs have not been compared with each other, lenvatinib appears to have greater efficacy than sorafenib.49 Adverse effects of the two drugs make the maintenance of full-dose therapy a challenge. The effects of the drugs on quality of life and the longterm cumulative toxic effects remain to be fully explored.
Phase 2 trials of other multikinase inhibitors that target vascular endothelial growth factor (VEGF)
Sorafenib and lenvatinib are thought to act by suppressing angiogenesis, because they inhibit VEGF receptors 1, 2, and 3. They also have distinct activity profiles against other kinases. Consequently, the therapeutic window with which they inhibit their respective targets affects clinical outcomes in ways that are poorly understood.
Poorly differentiated thyroid carcinomas are aggressive and are defined histologically by a combination of architectural and high-grade features (high mitotic rate and presence of necrosis).62,63 Poorly differentiated thyroid carcinomas represent approximately 6% of thyroid cancers and are associated with a mean survival of 3.2 years. Radioiodine therapy is of limited benefit. Most patients require systemic therapies that are similar to those described for differentiated thyroid carcinomas. Anaplastic thyroid carcinomas account for approximately 1% of thyroid cancers and are associated with a mean survival of 6 months. They are refractory to radioiodine, and traditional chemotherapy and radiotherapy are of limited benefit.64 Anaplastic thyroid carcinomas probably arise from preexisting differentiated or poorly differentiated thyroid carcinomas (Fig. 3) and
The genetic complexity of anaplastic thyroid carcinomas underscores their extreme virulence. When possible, these tumors should be resected and the patient treated with locoregional radiation therapy and chemotherapy with taxanes, either alone or in combination with carboplatin or doxorubicin.65 In patients with unresectable disease, preservation of the airway is critical, and palliative therapy is often the only option. Despite their genomic complexity, some anaplastic thyroid carcinomas retain dependence on the genetic drivers,66,67 and it is important to consider enrollment in experimental trials early in the course of disease. Candid discussions with patients and families about the extent and intensity of medical interventions and the option of home or institutional hospice care are important aspects of treatment.
Pathogenesis Medullary thyroid carcinoma accounts for 3 to 5% of thyroid cancers. In 75% of patients, the medullary thyroid carcinoma is sporadic, usually developing in the fourth to sixth decade of life. Less often, medullary thyroid carcinoma is the dominant component of the hereditary multiple endocrine neoplasia (MEN) type 2 syndromes, MEN2A and MEN2B (Table 2).68-77 MEN2A accounts for 95% of the cases of MEN type 2 and has four variants: classical MEN2A, MEN2A with Hirschsprung’s disease, MEN2A with cutaneous lichen amyloidosis, and isolated familial medullary thyroid carcinoma. MEN2B is characterized by a typical physical appearance and associated abnormalities.
RET, a gene encoding a receptor tyrosine kinase, is the dominant oncogene in medullary thyroid carcinoma. More than 100 gain-of-function RET mutations have been reported in patients with medullary thyroid carcinoma, including germline mutations in patients with hereditary disease and somatic mutations in patients with sporadic disease (Table S1 in the Supplementary Appendix, available with the full text of this article at NEJM.org).78
Medullary thyroid carcinoma cells secrete calcitonin and carcinoembryonic antigen (CEA). Serum levels of these markers are directly related to the parafollicular or C-cell mass and are useful in screening family members who are at risk for medullary thyroid carcinoma, in detecting persistent or recurrent medullary thyroid carcinoma after thyroidectomy, and in monitoring the response to local or systemic therapy.
Ultrasonography and cytologic testing of thyroid nodules by means of fine-needle aspiration are the preferred tests for the diagnosis of medullary thyroid carcinoma. If cytopathological testing is inconclusive, immunohistochemical testing for calcitonin in aspirated cells or the measurement of calcitonin in the washout fluid of the fineneedle aspiration may be diagnostic.80
Surgery is the primary treatment for patients with sporadic or hereditary medullary thyroid carcinoma and ranges from thyroid lobectomy (in selected patients with sporadic disease), to total thyroidectomy with or without central neck dissection, to total thyroidectomy with central neck dissection and unilateral or bilateral lymphnode–compartment dissection. The type of operation depends on the age of the patient and the extent of disease as determined by means of physical examination, imaging of the neck, and measurement of serum calcitonin levels.78,83 In families with MEN2A or MEN2B, prophylactic thyroidectomy is indicated in clinically normal children who inherit a mutated RET allele. The age of onset depends to some extent on the specific RET mutation; however, given a specific RET mutation, the age of onset varies among and even within families.
After thyroidectomy, patients are evaluated at 6-month to yearly intervals by means of physical examination and measurement of serum calcitonin levels. An undetectable serum calcitonin level indicates the absence of C cells, whereas a detectable level, even in the normal range, indicates the presence of residual C cells in a thyroid
Although many patients with metastatic medullary thyroid carcinoma can be followed expectantly, it is important to treat those who have progressive or symptomatic disease with systemic therapy. Standard chemotherapy is characterized by low rates of response of short duration and is seldom used as the initial treatment. The FDA approved the multikinase inhibitors vandetanib and cabozantinib on the basis of prolongation of progression-free survival, as compared with placebo, in separate, randomized, phase 3 clinical trials involving patients with advanced medullary thyroid carcinoma (Table 1).47,48 The responses were partial, and although some were durable, progressive disease developed in the majority of patients. No survival advantage has been shown with either drug. Also, the drugs are costly and are associated with toxic effects, often leading to dose reduction or termination of treatment. As with sorafenib and lenvatinib, the mechanisms of action of vandetanib and cabozantinib are unclear. The lack of specificity for RET diminishes their therapeutic window, because the inhibition of other kinases results in toxic effects at high doses. Current evidence indicates that the kinase activity of oncogenic drivers must be inhibited profoundly for maximal therapeutic benefit.86 Accordingly, there is growing interest in developing more selective RET kinase inhibitors, which may be more effective in patients with medullary thyroid carcinomas or other cancers that are driven by RET fusions, such as