Photodynamic therapy, or phototherapy, is an investigational cancer treatment that uses photosensitizing agents, such as porfimer (Photofrin). When administered intravenously, these agents are retained in higher concentrations in malignant tissue than in normal tissue. They are then activated by a light source, usually laser light, which penetrates body tissue. The light-activated agent then creates activated singlet oxygen molecules that are cytotoxic or harmful to body tissue cells. Because most of the photosensitizing agent has been retained in malignant tis-sue, a selective cytotoxicity can be achieved with minimal de-struction to normal tissues.
Cancers treated with phototherapy include esophageal cancers, endobronchial tumors, skin cancers, breast cancers, intraperitoneal tumors, and malignant central nervous system disease. The major side effect of therapy is photosensitivity for 4 to 6 weeks after treat-ment. Patients must protect themselves from direct and indirect sunlight to prevent skin burns. In addition, local reactions are ob-served in the area treated. Liver and renal function should also be monitored for transient abnormalities. As with any investigational treatment, emotional support and education are vital to assist the patient and family.