• Photoradiation therapy,
What is photodynamic therapy?
• Photodynamic therapy (PDT) is a treatment that uses
a drug, called a photosensitizer or photosensitizing
• Photosensitizers are exposed to a specific wavelength of
light, photoactivation causes the formation of singlet
oxygen, which produces peroxidative reactions that can
cause cell damage and death.
4. How is PDT used to treat cancer?
PDT essentially has three steps :
– Application of photosensitizer drug.
– Light activation.
• First, a light sensitizing liquid, cream, or intravenous
drug (photosensitizer) is applied or administered.
• Second, there is an incubation period of minutes to days.
• Finally, the target tissue is then exposed to a specific
wavelength of light that then activates the
• A wide array of photosensitizers for PDT exist.
• Some examples include:
aminolevulinic acid (ALA), Silicon Phthalocyanine Pc 4,
mono-L-aspartylchlorin e6 (NPe6), Benzoporphyrin derivative ,etc.
• Several photosensitizers are commercially available for
clinical use, such as:
Allumera, Photofrin, Visudyne, Levulan, Foscan, Metvix, Hexvi
x, Cysview, and Laserphyrin,etc.
• with others in development,
e.g. Antrin, Photochlor, Photosens, Photrex, Lumacan, Cevira, V
isonac, BF-200-ALA. Amphinex. Also Azadipyrromethenes.
6. • The light used for PDT include laser.
• Laser light can be directed through fiber optic cables
(thin fibers that transmit light) to deliver light to areas
inside the body.
• Other light sources include intense pulsed light, lightemitting diodes (LEDs), blue light, red light, and
many other visible lights (including natural sunlight).
10. • Photodynamic activation of macrophage like cells
contributes to an effective outcome of PDT treatment. The
possibility for an enhancement of macrophage activity by
photosensitization with meta-tetra(hydroxyphenyl)chlorin
(mTHPC) (1 μg ml–1) was studied, monocyte cell line
differentiated into macrophages.
• Pyropheophorbide-a methylester (PPME) is a
photosensitizers, photosensitization triggered apoptosis of
colon cancer cells via DNA laddering, PARP cleavage,
caspase activation and mitochondrial release of cytochrome
11. • 2-[1-hexyloxyethyl]-2-devinyl
(HPPH) to induce proinflammatory cytokines and
chemokines, as well as adhesion molecules, known to be
involved in neutrophil migration, results in the rapid
induction of an inflammatory response that is considered
important for the activation of antitumour immunity.
• Foscan® (mTHPC) photosensitized macrophage activation: enhancement of phagocytosis,
nitric oxide release and tumour necrosis factor--mediated cytolytic activity,
British Journal of Cancer Research Article (01 Sep 1999).
• Nitric oxide production by tumour tissue: impact on the response to photodynamic therapy,
British Journal of Cancer Research Article (01 Jun 2000).
• Mechanism of colon cancer cell apoptosis mediated by pyropheophorbide-a methylester
photosensitization Oncogene, Original Article (06 Jul 2001).
• Role of cytokines in photodynamic therapy-induced local and systemic inflammation,
British Journal of Cancer Original Article (02 Jun 2003).
12. What types of drugs and cancer are
currently treated with PDT?
• Porfimer sodium, BPD verteporfin - Cancer of the
esophagus (the swallowing tube), Barrett esophagus (a
pre-cancerous condition that may lead to esophageal
cancer), non-small cell lung cancer or endobronchial
• Aminolevulinic acid (ALA or Levulan), Methyl
ester of ALA (Metvixia® cream) - actinic keratosis
• Pyropheophorbide-a methylester (PPME) - colon
It has some advantages, such as:
• It has no long term side effects when used properly.
• It’s less invasive than surgery.
• It usually takes only a short time and is most often done as an
• It can be targeted very precisely.
• Unlike radiation, PDT can be repeated many times at the same
site if needed.
• There’s little or no scarring after the site heals.
• It often costs less than other cancer treatments.
• PDT is currently used in a number of medical fields, including
oncology (cancer), dermatology (skin), and cosmetic surgery.
14. What are the limitations of PDT?
• The light needed to activate most photosensitizers
cannot pass through more than about one third of an
inch of tissue (1 centimeter).
• For this reason, PDT is usually used to treat tumors on
or just under the skin or on the lining of internal organs
• PDT is also less effective in treating other tumors,
because the light cannot pass far into these tumors.
• PDT is a local treatment and generally cannot be used
to treat cancer that has spread (metastasized).
15. complications or side effects?
• Drugs makes the skin and eyes sensitive to light for
approximately 6 weeks after treatment.(Thus, patients
are advised to avoid direct sunlight and bright indoor
light for at least 6 weeks.)
• Photosensitizers tend to build up in tumors and the
activating light is focused on the tumor. As a result,
damage to healthy tissue is minimal.
• However, PDT can cause burns, swelling, pain, and
scarring in nearby healthy tissue.
• Other side effects include coughing, painful breathing,
trouble swallowing, stomach pain, or shortness of
breath; these side effects are usually temporary.
16. Future hold for PDT…
• Researchers continue to study ways to improve the
effectiveness of PDT and expand it to other cancers.
• Clinical trials (research studies) are under way to evaluate
the use of PDT for cancers of the brain,
skin, prostate, cervix, and peritoneal cavity (the space in
the abdomen that contains the intestines, stomach, and liver).
• Other research is focused on the development of
Photosensitizers that are more powerful, more specifically
target cancer cells, and are activated by light that can
penetrate tissue and treat deep or large tumors.
• Researchers are also investigating ways to improve
equipment and the delivery of the activating light.
• Dolmans DE, Fukumura D, Jain RK. Photodynamic therapy
for cancer. Nature Reviews Cancer 2003; 3(5):380–387.
• Wilson BC. Photodynamic therapy for cancer:
principles. Canadian Journal of Gastroenterology 2002;
• Vrouenraets MB, Visser GW, Snow GB, van Dongen GA.
Basic principles, applications in oncology and improved
Research 2003; 23(1B):505–522.
• Wei Li, Qingyong Ma, and Erxi Wu. Perspectives on the Role
of Photodynamic Therapy in the Treatment of Pancreatic
Cancer. Received 15 May 2011; Revised 25 July 2011;
Accepted 1 August 2011.