Anal canal carcinoma ppt.according to NCCN guidelines,&ref from std textbooks like gunderson,devita,perez,leibel etc.

1. ANAL CARCINOMA
Dr.AADITYA PRAKASH
DNB Resident, Radiation Oncology
BMCHRC, Jaipur

2. ANATOMY
• Anal canal extends from the
anorectal ring (dentate line) to the
anal verge(3-4 cm).
• Regions:-
•Intraanal lesions:-Cannot be
visualized or only slightly visualized with
gentle traction on the buttocks
•Perianal lesions:-Completely visible
–Within a 5-cm radius of anal
opening with gentle traction
•Skin lesions:-
–Outside of the 5-cm radius

3. INTRODUCTION
• Cancers of the anal region account for
1% to 2% of all large bowel cancers
and 4% of all anorectal carcinomas.
I. squamous cell carcinomas:- 75% -
80%
II. Adenocarcinomas:- 15%
• There is a slight female predominance
with 1. 7 cases per 1 00,000 women
compared with 1 .4 per 1 00,000 men
per year
• Anal canal cancer most commonly
develops in patients 50 to 60 years
of age.
• The corresponding 5-year relative
survival rates were :-
I. 80.1 % for localized disease,
II. 60.7% for regional lymph nodes,
29.4% for distant metastasis,
III.5 5 . 4 % for unstaged disease.

4. INTRODUCTION
• Risk Factors: >10 sexual partners,
history of anal warts, history of
anal intercourse < age 30 or with
multiple partners, history of STD.
• HPV: strongly associated with SCC
and may be requisite for disease
formation. High-grade
intraepithelial lesions are
precursors.
• In particular HPV-16, 18 as in
cervical cancer.
• The HPV viral proteins E6 and E7 inhibit
tumor suppressor p53 and retinoblastoma
proteins, respectively, and this disrupts
normal cell-cycle regulation.
• AIDS is associated with anal cancer, likely
through an association with
immunodeficiency in the setting of HPV
coinfection . Increased risk if CD4 < 200.

5. INTRODUCTION
• The incidence of anal cancer is also much
higher (up to 35 per 1 00,000) in men who
practice anal-receptive sexual
intercourse(MSM), and those who are
human immunodeficiency virus (HIV) -
positive have twice the risk than those
who are HIV-negative.
• Cigarette smoking has also been
implicated as a risk factor for the
development of anal cancer in a number
of case-control studies. The risk is
increased fivefold compared with controls.
• An association between anal cancer and
benign anal conditions (e.g., hemorrhoids,
anal fissure, or fistula) has been reported
frequently and chronic irritation or
inflammation of the anal tissue has been
assumed to play a role in anal
carcinogenesis.
• In a Danish population-based study,
patients with anal fissure, fistula, perianal
abscess, or haemorrhoids were found to
be at increased risk for anal cancer.

6. PATHOLOGY
• Anal cancers occur between the
anal verge and 2 cm beyond the
dentate line; tumors occurring
further from the dentate line are
called rectal cancers.
• Adenocarcinomas can arise from
anal crypts and should be treated
as a rectal cancer though with a
higher risk of inguinal node spread,
given their location and lymphatic
flow compared with rectal
adenocarcinomas.

7. PATHOLOGY
• Primary anal melanoma is a rare tumor that
accounts for only 1% of all anal cancers. Anal
melanoma is similar to melanoma of the skin
and is characterized by the distant spread of
disease.
• Outcome is poor after wide local excision or
abdominoperineal resection, with just a 10%
survival in most series at 5-year follow-up.
• Perianal skin and anal margin tumors include
squamous cell carcinoma, giant condyloma
(verrucous carcinoma), basal cell carcinoma,
Bowen disease, and Paget disease.

8. PATHOLOGY
• Classification of epidermoid anal cancers on
the basis of morphologic :-
I. transitional cell carcinoma,
II. basaloid carcinoma, and
III. mucoepidermoid carcinoma.
• These tumors all arise from the anal transition
zone and are often grouped together as
cloacogenic carcinoma.
• The World Health Organization (WHO) (3rd &
4th edi.)classification of malignant epithelial
tumors of the anal canal includes :-
• squamous cell carcinoma,
• adenocarcinoma,
• small cell carcinoma, and
• undifferentiated carcinoma.

9. PATHWAYS OF TUMOR SPREAD
• Anal cancer tumors spread by
I. direct extension to surrounding tissues,
II. lymphatic dissemination to pelvic and
inguinal lymph nodes, or
III. hematogenous spread to distant viscera.
• At diagnosis, about half of all anal cancers
have been found to invade the anal sphincter
or surrounding soft tissue. Although
Denonvilliers fascia is usually an effective
barrier to prostatic invasion in men, direct
extension to the rectovaginal septum is a
common occurrence in women.

10. PATHWAYS OF TUMOR SPREAD
• The superficial inguinal nodes are the primary
drainage basin for that part of the anal canal
distal to the dentate line.
• Lymphatic drainage around the dentate line
occurs to lymphatic plexuses of the rectal
mucosa and along the pathway of the inferior
and middle hemorrhoidal vessels to obturator
and hypogastric lymph nodes.
• Lymphatic connections also join the anus to
presacral , external iliac, and deep inguinal
nodes.

11. PROGNOSTIC FACTORS
• Mawdsley et al:-244 of 577 anal cancer
tissue samples were assessed from the
United Kingdom Coordinating Committee
on Cancer Research (UKCCCR) ACT I
study for the expression level of p53 , Bcl-
2, thymidylate synthase, thymidine
phosphorylase, and Ki-67. High
expressions of p53 were associated with
decreased DFS in the multivariate analysis.
However, Bcl-2, thymidylate synthase, Ki-
67, and thymidine phosphorylase
expressions had no prognostic value.
• Boman et al.:-reviewed 114 patients
treated with APR and demonstrated that
tumor size inversely related to survival and
was strongly associated with stage.
• Radiation Therapy Oncology Group (RTOG)
98 -11 trial:-tumor-related prognosticators for
poorer OS included node-positive cancer, large (
> 5 cm) tumor diameter, and male gender.
Tumors greater than 5 cm in diameter,
regardless of nodal status, had a higher
colostomy rate and inferior disease-free survival
(DFS ).
• Touboul et al.:- larger tumors yielded inferior
10-year OS (T1 86 % ; T2, 82.5 % ; T3, 56. 8 % ;
and T4, 45 %). In addition, survival was
significantly better in patients with tumors 4 cm
or less in diameter as compared to tumors
greater than 4 cm.

12. CLINICAL PRESENTATION
• The most common presenting symptoms are bleeding (45%) and anal
pain(30%). Other less common symptoms include pruritus , palpable
mass ,anal swelling and changes in bowel habits are the main
symptoms.
• It is common for patients and their physicians to attribute such
symptoms to hemorrhoids for many months preceding the diagnosis,
underscoring the importance of performing a simple anorectal
examination for patients with such symptoms.

13. Workup for Anal Canal Cancer
• PET imaging is useful in further evaluating the
extent of the primary tumor and the presence of
regional lymph node metastases, and distant
metastases, as well as in evaluating the response
to therapy.
• For patients with HIV risk factors, a
determination of HIV status should be made
before the initiation of therapy.
• Female patients should be subjected to a
gynecologic examination to exclude other HPV-associated
cancers.
• Counselling for loss of fertility for men and
women.

14. Workup for Anal Canal Cancer
• Surgery for the initial diagnosis and
staging of anal canal tumors should be
limited to a biopsy of the primary tumor
and evaluation of the inguinal lymph
nodes.
• Clinically enlarged inguinal lymph nodes
should be aspirated. If the cytology is
nondiagnostic or demonstrates only
benign disease, an open excisional biopsy
of 1 or 2 lymph nodes is recommended.
• Under no circumstances should a formal
lymph node dissection be performed for
the initial evaluation of suspicious nodes,
as it can increase the morbidity of
radiation and has no therapeutic value.

15. AJCC TNM STAGING ,7TH

16. AJCC TNM STAGING ,7TH
• Note: Direct invasion of the rectal wall,
perirectal skin, subcutaneous tissue, or
the sphincter muscle(s) is not classified as
T4.

17. TREATMENT OF LOCALIZED
SQUAMOUS CELL CARCINOMA
OF THE ANAL CANAL
• Until the late 1970s, the conventional
treatment for anal canal cancer was an
APR. Nigro et al. challenged this practice
with a report of patients with squamous
cell cancer of the anal cancer who
following preoperative treatment with
30 Gy plus concurrent fluorouracil (5-FU)
and mitomycin-C were found to have a
pathologic complete response at the time
of surgery.
• Combined Modality Therapy has been the
standard of care since the 1980s, a review
of 38,882 patients with anal cancer
registered in the National Cancer Data
Base from 1985 to 2005 revealed that only
75% received that treatment.:-
• Those treated with CMT (plus surgery)
had higher 5-year survival rates compared
to those who did not receive CMT (65%
versus 58%, P < .0001).

19. ROLE OF INDUCTION CHEMOTHERAPY
• NCCN:-
• “…Induction chemotherapy preceding chemoradiation may be beneficial in
subset of patients with T4 cancer. 5-year colostomy free survival rate was
significantly better in T4 patients who received induction 5-FU/ cisplatin
compared to those did not.(100% vs. 38+/-16.4%.P=.0006)”

20. NOVEL BIOLOGICAL RADIOSENSITIZING
AGENTS
• Cetuximab , a monoclonal chimeric antibody against EGFR, is effective in
combination with radiotherapy in treating squamous cell carcinoma of the
head and neck.
• A small phase 1 study of anal cancer patients showed that the addition of
cetuximab to cisplatin and 5-FU chemoradiation is safe and feasible . This
phase 1 study had patients with T2N2 - 3 ,T3N0-3, and T4NO. A 78 %
pathologic complete response rate was reported. KRAS and BRAF mutation
appear to be infrequent, reinforcing the potential benefit of EGFR inhibitors.

21. SURGERY
• Surgery is the principal treatment for anal
intraepithelial neoplasia but retains only a
limited place in the initial management of
primary invasive anal cancer.
• Local excision, preserving anorectal
function, is possible in some patients,
although this is now usually restricted to
small well-differentiated squamous cell
cancers that have not invaded the
sphincter muscles and are located distal
to the dentate line.
• This approach is based on the finding in
surgical series that pararectal or superior
hemorrhoidal system lymph node
metastases were associated with <5% of
well-differentiated squamous cell cancers
<2 cm in size.
• The combination of local surgery and RT
and chemotherapy has resulted in
regional control rates in the groin of 80%
or better. However, 5-year survival rates
are usually 20% less than in those who do
not present with inguinal node
metastases.
• Surgery is reserved for failure to achieve
complete response or for local failures.

22. RADIATION THERAPY
• Localization, Immobilization, and
Simulation
• Immobilization and patient position
• Supine with arms across the chest or prone in a belly
board in an alpha-cradle or other immobilization
device, arms extended. If using the prone setup for
primary fields, may consider supine positioning for
the boost (which is typically away from small bowel)
so that desquamated patients may be positioned
more comfortably.
• Contrast agents and markers
I. Oral contrast to delineate the small bowel.
II. Barium enema to delineate the tumor.
III. IV contrast to delineate the tumor and LN.
IV. Anal marker to delineate the anus.
V. Wire to involved inguinal LN.
VI. Bladder should be moderately filled.
• Target Volume Definitions
• GTV:- Primary tumor clinically positive LN seen on
planning CT (>1 cm short axis diameter).
I. PET or MRI fusion typically aides in GTV
delineation.
II. Colonoscopy/anoscopy reports may help
determine tumor location.
• CTV:- LN at risk include common iliac, external iliac,
internal iliac, presacral, mesorectal, perianal, and
inguinal.
I. CTV = 2.5 cm expansion on primary tumor and 1
cm expansion on involved nodes
• PTV
• PTV = CTV + 1cm

23. RADIATION THERAPY
• GUIDELINES:-
• Whole Pelvic Field
• Posterior-anterior:-
• Superior border:- L5/S1 junction for the first 30.6 Gy. This is then decreased
to the inlet of the true pelvis (bottom of the sacroiliac joints) for the
remaining 14.4 Gy.
• Lateral borders:- 1.5 cm lateral to the widest bony margin of the true pelvic
side walls. The lateral border is then extended to include the lateral inguinal
nodes. These nodes should be outlined with wire in order to help identify
them.
• Inferior border:-minimum 2.5 cm below the anal verge or the inferior extent
of the primary tumor—whichever is most inferior.

24. GUIDELINES
• Laterals:-
• Superior border:- Same as posterior-anterior field.
• Inferior border:- Same as posterior-anterior field.
• Posterior border:- 1-1.5 cm behind the anterior body sacral margin.
• Anterior border:- Posterior margin of the symphysis pubis (to treat only the internal
iliac nodes).
• Blocking:-
• Blocks are used to spare the posterior muscle and soft tissues behind the sacrum,
to reduce the amount of dose inferior to the symphysis pubis, and to decrease the
amount of small bowel treated both superiorly and anteriorly

25. GUIDELINES
• Perineum:-
• Never use an electron or photon boost for the perineum—there will be overlap
between the electron and photon fields. The perineum should be treated in the
photon fields.
• Inguinal Nodes Boost Field:-While the patient is in the supine position, the medial
and lateral inguinal nodes are outlined with a 2-cm margin in all directions.
• Primary Tumor Boost for Combined-Modality Therapy Salvage:- If the Radiation
Therapy Oncology Group recommendations for combined-modality therapy
salvage are followed, then an additional 9 Gy (concurrent with 5-fluorouracil-cisplatin)
are delivered. With a multiple-field technique, the field includes the
primary tumor plus a 3-cm margin in all directions.

26. GUIDELINES
UPPER BORDER
LOWER BORDER
MINI. 2.5 CM MARGIN AROUND ANUS & TUMOR

27. CONE DOWN FIELD BORDERS
• Lower superior border to the bottom of SI
joints.
• Inferior and lateral borders remain the
same.
• Boost field
Indicated for T3, T4, N1, or T2 lesions with
residual disease after 45 Gy.
 Use 2 cm margin on GTV via AP/PA, 3-
field (opposed laterals and PA –lowest
anterior skin dose), or 4-field
(AP/PA/laterals) approach.
• 4-field technique: This usually
requires higher electron
supplement to the inguinal nodes,
which can result in greater inguinal
desquamation.

28. Volumetric Planning Goals
• 95% of the PTV should receive at least 95% of the prescription dose.
• No portion of the PTV should receive less than 85% of the prescription dose.
• 99% of the CTV should receive at least 95% of the prescription dose.
• 0.1 cc of tissue is limited to 115% of the prescription dose.
• 1.0 cc of tissue (or 5% of the PTV) is limited to 110% of the prescription dose.
• 5 cc of tissue (or 10% of the PTV) is ideally limited to 105% of the prescription dose.
• For external genitalia, attempt to limit
 50% to less than 20 Gy
95% to less than 40 Gy
• For iliac crest, may attempt to limit
50% to less than 30 Gy
 95% to less than 50 Gy

29. DOSE / FRACTIONATION (NCCN)
• CTV to 45 Gy/1.8 Gy/fx
• Field reduction to cone down after 30.6 Gy.
• T3, T4, or T2 lesions with residual disease after 45 Gy should receive an additional 9
to 14.4 Gy to the GTV via boost field.
• T2 dose goal, 45 to 50.4 Gy
• T3 dose goal, 54 Gy
• T4 dose goal, 54 to 59.4 Gy
• Clinically negative inguinal LN should receive a minimum of 36 Gy, measuring
prescription depth on CT classically, 3 cm has been used (this may underdose
thicker patients).

30. DOSE / FRACTIONATION (NCCN)
• Clinically positive inguinal LN should
receive a minimum of 45 Gy.
• Boost additional 5.4 to 9 Gy depending on
LN size and clinical response.
• Clinically positive pelvic LN may be
boosted along with primary boost field for
an additional 5.4 to 9 Gy above 45 Gy CTV
dose depending on LN size and clinical
response.
• RTOG 0529 (employs IMRT using dose-painting
technique):
• For T2N0:
• PTVA (primary tumor): 50.4 Gy in 28 fx (1.8 Gy/fx)
• Nodal PTV: 42 Gy in 28 fx (1.5 Gy/fx)
• For T3/4 N0:
• PTVA (primary tumor): 54 Gy in 30 fx (1.8 Gy/fx)
• Nodal PTV: 45 Gy in 30 fx (1.5 Gy/fx)
• For N+:
• PTVA (primary tumor): 54 Gy in 30 fx (1.8 Gy/fx)
• Nodal PTV (uninvolved nodes): 45 Gy in 30 fx (1.5
Gy/fx)
• Nodal PTV (≤3 cm): 50.4 Gy in 30 fx (1.68 Gy/fx)
• Nodal PTV (>3 cm): 54 Gy in 30 fx (1.8 Gy/fx)

31. RTOG 0529: A Phase 2 Evaluation of Dose-Painted Intensity Modulated
Radiation Therapy in Combination With 5-Fluorouracil and Mitomycin-C for
the Reduction of Acute Morbidity in Carcinoma of the Anal Canal
Anus cancer
Nodes
High Risk Node
DP-IMRT was associated with significant sparing of acute grade 2+
hematologic and grade 3+ dermatologic and gastrointestinal toxicity.
IJROBP 2013;86:27

32. RTOG 0529 (IMRT with 5-FU and MMC)
VS. RTOG 98 - 11
• 77% of patients experienced grade 2 or higher
gastrointestinal/ genitourinary ( GVGU) acute
adverse events (AEs) that were equal to that
noted in the MMC arm of RTOG 9 8 - 1 1 ( 76 %
).
• There was a statistically significant reduction
in grade 3 or higher GVGU AEs with IMRT, 2 1
% versus 3 6 % RTOG 9 8 - 1 1 (P < .00 8 ) , and
grade 3 or higher dermatologic AEs, 2 1 %
versus 47% RTOG 9 8 - 1 1 (P < .000 1 ) .
• The use of IMRT with 5-FU and MMC resulted
in significant reduction in grade 3 +
dermatologic and GVGU acute toxicity.

33. BRACHYTHERAPY
• Brachytherapy is an ideal method by which to
deliver conformal radiation for anal cancer
while sparing the surrounding normal
structures such as small intestine and bladder.
In most series, patients received 30 to 55 Gy of
pelvic radiation with or without 5-
FU/mitomycin-C or cisplatin followed by a 15
to 25 Gy boost with Ir192 afterloading
catheters.
• In a retrospective review from Bruna et al, 71
patients with a variety of T and N
classifications were treated with a median of
45 Gy external beam to the pelvis with or
without cisplatin-based chemotherapy,
followed by a median of 17.8 Gy pulsed dose
rate brachytherapy.
• The 2-year actuarial local control was 90%;
however, 17% had grade 3+ complications.

34. Side Effects of Pelvic Radiation
Radiation fields
Radiation may hit the
small bowel causing
some cramps, diarrhea
and fatigue
High dose
area

35. Side Effects of Pelvic
Radiation
Radiation fields
Radiation may hit the bladder and
rectum causing urinary burning or
frequency and ano-rectal
irritation and skin burning
High dose area
In pre-menopausal women, radiation is likely to
effect ovarian function and should not be used if
the woman is pregnant.

36. TREATMENT OF THE HIV-POSITIVE PATIENT
• HIV-positive patients should receive lower
doses of radiation and chemotherapy because
of a concern that standard therapy may not be
tolerated (Melbye M, Cote T, Kessler L, et
al: AIDS/Cancer Working Group. High incidence
of anal cancer among AIDS
patients. Lancet 1994; 343:636-639)
• Although it is not necessary to alter standard
management recommendations, HIV-infected
patients, especially those with a CD4 count less
than 200/mcL, should be monitored for an
increased risk of toxicity when treated with
chemoradiation. (NCCN)

37. TREATMENT OF THE HIV-POSITIVE PATIENT
• George Washington University Medical Center
and the affiliated Veterans Administration
hospital revealed an 80% grade 3 or 4 major acute
toxicity rate for patients with HIV treated with 5 -
FU, MMC, and radiation compared to 30 % in
patients without HIV. Late complications were
higher patients with HIV compared to patients
without HIV (40% vs. 1 6 % ; NS ) .
• Other retrospective analyses show similar
findings, most notably in patients with low
pretreatment CD4 counts.
• One multicenter retrospective study evaluating
treatment outcomes in HIV-positive patients
treated consecutively between 1997 and 2006,
demonstrated a trend toward decreased cancer-specific
survival at 5 years (HIVpositive,68 % ;
HIV-negative, 79 % ; P = .09).
• Long-term LC was also worse in the HIV-positive
group, with a 5-year LC rate of 38 % in patients
with HIV versus 87 % in those who were HIV-negative.

38. SALVAGE THERAPY FOR LOCAL RECURRENCE
• Most patients undergo an APR and a
permanent colostomy is established with
creation of a large pelvic floor defect.
• Tumors that invade local structures such
as the vagina or prostate should be
resected with negative margins and this
often involves multivisceral resection.
• The OS at 5 years following resection is in the
range of 30 % to 64 % , with DFS rates i n the
range o f 30 % t o 40 % .
• The most important prognostic factor of
survival after resection is the status of the
margin, and patients with negative margins
(R0) have up to 75 % 5-year OS.
• Predictors of a poor OS outcome following
surgery are inguinal lymph node status, tumor
size greater than 5 cm, adjacent organ
involvement male gender, and more numerous
comorbidities.

39. Diagnostic and treatment algorithm for newly diagnosed anal
cancer

40. MANAGEMENT OF METASTATIC DISEASE
• Systemic chemotherapy for metastatic
squamous cell carcinoma of the anus is
generally similar to other metastatic squamous
histology, such as lung or head and neck
cancers.
• Cisplatin and 5-FU have been reported to
achieve an 11 % complete response and 61 %
partial response rate.
• Hainsworth et al:- treated 60 patients with the
combination of carboplatin, paclitaxel, and 5 -
FU in a phase 2 study with an overall response
rate of 90 % .

41. SQUAMOUS CELL CANCER OF THE ANAL
MARGIN
• Anal margin is usually defined as the area
extending from the anal verge to 5 cm out.The
onset of the disease is usually in the seventh
and eighth decade with a slight female
predominance. In most cases, these tumors
are well differentiated and slow growing and
distant metastases are rare.
• Inguinal lymph nodes are the primarily nodal
drainage for anal margin cancers, and regional
nodal metastasis is directly related to the size
of the tumor.
• The treatment of anal margin cancer needs to
be individualized based on the size and
location. Wide local excision with a 1 -cm
margin is often sufficient for small and
superficial tumors. When the tumor is
advanced, or located close to the anal canal
and sufficient surgical margin cannot be
achieved, combined modality treatment or
APR may have to be considered.

42. SQUAMOUS CELL CANCER OF THE ANAL
MARGIN
• Papillon and Chassard reported on 8 patients
with T1 or T2 lesions that were treated with
either radium implant brachytherapy alone (six
patients) or in combination with external-beam
radiation (two patients ) .
• The local control rate was 100 % . In this study,
an additional 36 patients were treated with
external radiation with 5-FU and MMC. The
cure rate for T 1 , T2, and T3 lesions were 100 %
, 84 % , and 50 % , respectively.
• Cummings compared radiation alone versus
chemoradiation retrospectively in 29 patients;
1 1 patients were treated with radiotherapy
alone and 1 8 patients received 5-FU, MMC,
and radiotherapy.
• After a median of 7 years of follow-up, the
local control rate was 64 % for the radiation
group and 88 % for the chemoradiation group.
The local control rate was inversely associated
with larger cancers (T1-T2, 100 % ; T3 ->5-10
cm, 70 % ; T3 ->1 0 cm, 40 % ) .

43. ADENOCARCINOMA OF THE ANAL CANAL
• Adenocarcinoma arises from the columnar epithelium of the anal canal and its incidence is low
accounting for less than 5 % of all anal malignancies.
• Extension of rectal cancer into the anal canal is the more common presentation. Occasionally,
adenocarcinoma may occur in patients with ulcerative colitis or Crohn disease who have ileal pouch-anal
anastomosis.
• APR should be offered for early-stage disease.
• For locally advanced disease (T3 or any T with N + ), a multimodality approach should be considered.
Patients treated with APR had significantly improved 5-year OS than those treated with radiation
alone.

44. MELANOMA OF THE ANORECTAL REGION
• Anorectal melanoma is rare and accounts for less than 3 % of all malignant melanomas
and less than 1 % of all anal canal tumors.
• The 5 -year OS rate is generally less than 20 % . The initial stage at presentation largely
determines OS.
• Ross et al. from the M. D. Anderson Cancer Center reviewed a series of 32 patients with
melanoma treated with either APR or local resection.
• Local recurrence was lower in the APR group (29 % for APR; 5 8 % for local excision) .
However, there was no difference in OS between the two groups ( 19 . 5 months for APR;
18 .9 months for local resection ) .
• Most authors recommend local excision of anorectal melanoma if adequate margins
could be achieved.

45. THANK YOU