This treatment method is used to open up esophageal or biliary blockages or treat small, shallow tumors in patients who cannot tolerate open surgery. In PDT, a drug called a photosensitizer is given to the patient intravenously and absorbed only by cancer cells over a few days. Using an endoscope, the surgeon exposes the lesion to a certain wavelength of light, which causes an active form of oxygen to be produced. This directly kills the cancer cells and also acts indirectly to damage the tumor's blood vessels, further destroying the cancer and limiting damage to surrounding healthy tissue.
PDT cannot be used for large or deep tumors. Risks include light sensitivity for about six weeks after treatment, trouble swallowing after treatment, swelling, pain, or scarring in healthy tissue. The endoscopist may also place a stent in the esophagus to open up any blockage and enable more comfortable swallowing.