Photodynamic Therapy

Mesothelioma Treatment with Photodynamic Therapy

One of the most frustrating characteristics of mesothelioma is that in spite of aggressive therapy, the disease recurs in most patients, especially if it is only treated with surgery. That’s the reason, say researchers in a study titled Photodynamic therapy for mesothelioma published in the September 2001 edition of Current Treatment Options in Oncology, that, “. . .one of the major considerations in the development of new treatments is the inclusion of aggressive local therapies. Photodynamic therapy (PDT), a local treatment modality, is being evaluated as an adjuvant (secondary) therapy to surgical resection.”

Localized treatments target the tumor directly. The benefits of this kind of therapy are that because it focuses on the tumor itself, it allows the doctor to administer more of it and it can be repeated without harming normal body tissues.

Photodynamic therapy uses a photosensitizing drug and red laser light to kill cancer cells. Photosensitizing drugs increase a tumor’s sensitivity to the laser light. The therapy is administered in two parts. During the first treatment session, the drug is given intravenously. Two days are allowed to elapse so that the drug can be absorbed by the tumor cells. Then, during the next treatment session, the doctor inserts a flexible fiber optic tube with a laser and magnifying lenses into the body called an endoscope. The doctor uses the instrument to shine the laser onto the diseased tissue. The laser combined with the drug causes a chemical reaction that eliminates the diseased cells.

According to the study, the effect of PDT is superficial because tissues cannot absorb light to any great depth. That is why this procedure is a good choice as a secondary therapy for tissue surfaces and body cavities after surgical debulking, removal of as much of the tumor as possible.

Another advantage, according to these researchers, is that it can be used to treat the lung surface after a pleurectomy; so that patients won’t have to undergo an extrapleural pneumonectomy. The difference between these two procedures is that the less invasive pleurectomy only removes part of the chest lining and some of the surrounding tissue, while extrapleural pneumonectomy is a removal of the diseased lung, part of the membrane covering the heart, part of the diaphragm, and part of the parietal pleura, the part of the membrane covering the lung that connects to the chest wall. It also requires a reconstruction of the diaphragm and the membrane covering the heart as part of the procedure.