Photodynamic Therapy as a New Treatment Approach in Cancer

Photodynamic therapy (PDT) is a treatment approach that uses a photosensitizer, and light, to kill cancer cells. The treatment consists of two stages. In the first stage, the photosensitizer is accumulated in cell, following topical or systemic administration. In the second stage, the sensitized tumor is exposed to light at a specific wavelength that is appropriate for the absorption spectrum of the photosensitizer. When this activated sensitizer transfers energy to molecular oxygen, reactive oxygen species are generated. Therefore, necrosis and/or apoptosis are induced in tumor cell. ROS can also stimulate the transcription and release of inflammatory mediators. There are different types of photosensitizer and each is activated by light of a specific wavelength. An ideal photosensitizer should be a pure compound, water-soluble to allow quality low manufacturing costs and good stability. It should have a absorption peak between 600 and 800-nm (red to deep red). Several photosensitizers are currently approved by the US Food and Drug Administration (FDA) to use with laser light. Wavelength determines how far the light can travel into the body. Therefore, each combination of photosensitizers and light wavelengths is used to treat different cancer types. PDT may also help by destroying the blood vessels around the cancer cells and by inducing the immune system to attack the cancer. Studies in clinic revealed that PDT, minimally invasive therapeutic procedure, can be curative particularly in early-stage tumors. It can help prolonged the life span and improve quality of life. To date, PDT is being tested in the clinic for use to treat cancers of the head and neck, brain, lung, pancreas, intraperitoneal cavity, breast, prostate and skin. The therapy can be used as an adjuvant therapy with conventional therapy such as surgery, radiation or chemotherapy. It can be concluded that PDT could be a promising cancer treatment modality with its curative potential. Key-words:Photodynamic Therapy, Laser, Photosensitizers, Cancer treatment