Mesothelioma Treatments

Mesothelioma Photodynamic Therapy

Photodynamic therapy is based on the principle that normal cells and cancer cells react differently to photosensitizing drugs. Photodynamic therapy uses light energy in combination with medication to destroy cancer cells while leaving healthy cells mostly unaffected.

During the photodynamic therapy treatment process, a patient is given a drug such as Photofrin that is a photosensitizer and makes cells sensitive to light. The treated cells are then exposed to light of specific wavelengths which make the cells produce a toxic form of oxygen that kills nearby cancer cells.

Photodynamic therapy begins with the injection of a photosensitizing drug that is administered intravenously. Over a period of 24 to 72 hours, the drug travels through the body and is absorbed by cells. Cancer cells react more strongly with the drug, causing them to absorb the photosensitizing drug faster than healthy cells..

After the drug injection has had time to work, the patient is treated with light that reacts to the photosensitizing drug. A physician directs a beam of light on the cancerous area. The treated cancer cells absorb the light, which causes them to produce a form of oxygen that is highly toxic to the cell, resulting in cell death. In addition, the therapy can damage blood vessels in the tumors starving the cancer cells of nutrients.

Photodynamic therapy is usually performed on an outpatient basis and is often used with other types of treatment such as surgery and chemotherapy. Due to the nature of this mesothelioma treatment, it is not effective for the treatment of cancer that has spread extensively throughout the body. The light emitted in this type of therapy is not high intensity and can only penetrate about three centimeters. Photodynamic therapy is most effective in treating single, localized cancers.

Side Effects of Photodynamic Therapy

Some drugs used in photodynamic therapy can make the eyes and skin 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 even a very brief 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 at least six weeks 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. This downside is outweighed, however, by the ability of the healthy tissue to recover more quickly than cancerous tissue. The healthy tissue regenerates and replaces the cancerous cells.

Additional side effects such as coughing, shortness of breath, trouble swallowing, painful breathing and stomach pain can also occur depending on the location of treatment. Other people also complain about a metallic taste in the mouth along with severe nausea.

Photodynamic Therapy in the Future

Because the type of light used in photodynamic therapy cannot penetrate deeply into skin and tissue, it is most effective in cancers that affect the skin or for cancers that are near the skin's surface (including some types of lung cancer). In addition, individuals with large tumors may not be suitable candidates for photodynamic therapy as the light is unable to penetrate throughout the tumor.

Medical research for photodynamic therapy seeks to increase the range of cancers for which the treatment can be used (including peritoneal mesothelioma) and to improve the efficacy of the therapy for treating larger tumors. Other research concentrates on the possibility of administering photodynamic therapy during surgery or by means of optical fibers that are guided directly into tumors.

One study found that combining surgical intervention and photodynamic therapy increased the survival results in patients with stage I or II pleural mesothelioma, but were less effective on more advanced mesothelioma. A demonstration of the advancements that are coming in the area of photodynamic therapy is demonstrated by the results of a study conducted in 2003. In that study it was shown that using Foscan-mediated PDT could be safely combined with surgery.

The researchers determined that unlike most other surgery-based multimodal treatments for mesothelioma, Foscan-mediated PDT provides the option of surgically reducing mesothelioma tumor size with a lung-sparing procedure rather than an extra pleural pneumonectomy (removal of the lung). The researchers strongly suggest that additional follow up studies be conducted to further document and expand this treatment. Every advance helps, and with further study, photodynamic therapy may become a standard treatment in the coming years.

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