Photodynamic therapy for mesothelioma

Photodynamic therapy (PDT) uses a light-activated drug to access and destroy cancer cells. The technology has been in use since the l990s; since its introduction the FDA has approved the use of the light-activated drug Photofrin (porfimer sodium) in treating the symptoms of non-small cell lung cancer. It is also approved to treat the symptoms in patients with esophageal cancer where surgery and radiotherapy are not a reasonable choice. The drug is injected and distributed throughout the body by natural methods. It leaves healthy cells earlier than cancer cells; at the point where healthy tissue is clear of the photosensitized medication a light is beamed on the cancerous tissue to activate the drug, which produces a type of oxygen that kills the cancer cells. The light is delivered from a fiber optic source attached to an endoscope and inserted through a minor incision. The light source can also be delivered to the inside of the lungs and the esophagus to treat cancer in those locations.

Different photosensitizing drugs respond to different wavelengths of light, and wavelength defines how far into the body the light can travel. The physician's choice of photosensitizer and wavelength are dictated by how much tissue the light must travel through to reach the impacted area. PDT may damage tumors in two other ways. It appears that the treatment may damage blood vessels in the tumor, thus denying it nutrients. It may also stimulate the immune system, causing the body to attack the tumor. The potential success of photodynamic therapy runs off the principle that normal cells and cancer cells react differently to photosensitizing drugs. Photodynamic therapy uses light energy to destroy cancer cells while leaving healthy cells largely unaffected. During the photodynamic therapy treatment process a patient is given drugs called photosensitizers, which make cells sensitive to light. The treated cells are then exposed to light of a specific wavelength, and this causes them to produce a particular form of oxygen that is toxic and kills nearby cancer cells.

Photodynamic Therapy as a Treatment for Mesothelioma:
Photodynamic therapy begins with the injection of a photosensitizing drug. This drug is administered intravenously into the bloodstream and over a period of 24 to 72 hours the drug travels throughout the body and is absorbed by cells. In general, cancer cells absorb the photosensitizing drug quicker than healthy cells. In addition, the drug remains in cancer cells longer than healthy cells. For these reasons, by the time the patient proceeds to the next stage of treatment, the drug is predominately present in cancer cells with low concentrations remaining in some healthy cells.

Photodynamic Therapy Side Effects:
Some drugs used in photodynamic therapy can make the eyes and skin very sensitive to light for up to six weeks after treatment. If the skin and eyes are not protected, they can become burned or blistered after just a few minutes of exposure to sunlight or bright indoor lights. For this reason, those undergoing photodynamic therapy are advised to avoid bright indoor lights and direct sunlight for six weeks or longer after treatment. Damage to normal, healthy tissue is minimal when photodynamic therapy is used because the treatment is highly specific. In some cases, the treatment may cause burns, pain, scarring, and swelling in nearby healthy tissue, as well as side effects such as coughing, shortness of breath, trouble swallowing, painful breathing, and stomach pain, depending on the location of treatment.