Photodynamic therapy

In addition, basic science and clinical work by dermatologists Yoram Harth and Alan Shalita and others has produced evidence that intense blue/violet light (405-425 nanometer) can decrease the number of inflammatory acne lesion by 60-70% in 4 weeks of therapy, particularly when the P.acnes is pretreated with delta-aminolevulinic acid (ALA), which increases the production of porphyrins. However this photodynamic therapy is controversial and apparently not published in a peer reviewed journal

PDT uses laser, or other light sources, combined with a light-sensitive drug (sometimes called a photosensitising agent) to destroy cancer cells.

A photosensitising agent is a drug that makes cells more sensitive to light. Once in the body, the drug is attracted to cancer cells. It does not do anything until it is exposed to a particular type of light. When the light is directed at the area of the cancer, the drug is activated and the cancer cells are destroyed. Some healthy, normal cells in the body will also be affected by PDT, although these cells will usually heal after the treatment.

PDT can be used to treat some cancers, or conditions that may develop into a cancer if not treated (precancerous). It is used when the affected area or the cancer is on or near the lining of internal organs. This is usually with cancers or conditions that affect:

• the skin (but not melanoma)
• the head and neck
• the mouth
• the lung
• the gullet (oesophagus)
• the stomach
• the bile ducts

Doctors are working to identify the types of cancer for which PDT is most effective. Research trials are taking place to look at new photosensitising agents, new laser and non-laser light treatments and ways of reducing the side effects.

Precancerous conditions PDT is used to treat precancerous conditions, such as Barrett's oesophagus and Bowen's disease of the skin.

Some research studies have used PDT to treat precancerous changes in the cells affecting the vulva (vulval intraepithelial neoplasia or VIN), the vagina and the anus.

Cancer In cancers that are being treated at an early stage, the aim of treatment may be to try to cure the cancer.

The aim of PDT for advanced cancer is usually to reduce symptoms by shrinking the tumour. In this situation PDT cannot cure a cancer.

PDT treatments for some cancers, such as prostate and pancreas, are still being researched.

Your doctor can advise you about whether PDT is an appropriate treatment in your situation, and whether you may be able to take part in any research trials.

PDT can safely be given to patients who have had other cancer treatments such as surgery, radiotherapy and chemotherapy.

source : http://en.wikipedia.org and http://www.cancerbackup.org.uk