Blinded by the Light

One of the latest treatments for cancer is called Photodynamic Therapy (PDT), which uses directed laser light instead of chemical toxins or radiation to destroy tumor cells. The patient is injected with a photosensitizing agent (which is medicalese for “light-sensitive drug”), which causes cells to become more light-sensitive. This drug is inert however, until activated by exposure to specific light wavelengths. Once this light is directed at the tumor, the drug goes into action, destroying the cancer cells. As is the case with traditional chemotherapy and radiation treatments, some healthy tissues around the area of the cancer are invariably destroyed; however, these generally regenerate and heal once treatment is completed. Currently, PDT is used to treat cancers on or near the lining of internal organs, including those of the esophagus, stomach, bladder and lung. Most ongoing research concerns the identification of other types of cancer that may respond to PDT.

Side effects of PDT include sensitivity to light; it may be necessary for patients to avoid the sun for up to two weeks following treatment. Mesothelioma is a special case because (A) it is typically not diagnosed until its advanced stage, and (B), is particularly aggressive; recurrence is all-too-common. So far, mesothelioma does not respond to any single treatment; a combination of different therapies has been necessary in order to slow the spread of the carcinoma. PDT is showing a great deal of promise in the treatment of mesothelioma. One of the reasons for this is the manner in which PDT is delivered; it allows physicians to treat the surface of the lung after the pleural lining has been removed, and can eliminated the need for removing lung tissue itself. However, by itself, PDT is apparently no better for mesothelioma patients than any other treatment alone; combination therapies and procedures will still be necessary for the time being.