Photodynamic Therapy (PDT)
Photodynamic therapy (PDT) is a minimally invasive, non-surgical way to treat lung cancer at the University of Wisconsin Carbone Cancer Center, the state's only comprehensive cancer center. PDT may also be offered to esophageal cancer patients to relieve symptoms of their cancer.
PDT uses a special drug, called a photosensitizer, and specific wavelengths of light to kill cancer cells. It can be a curative treatment for early-stage, non-small-cell lung cancer, in some cases sparing patients from surgery. For patients with inoperable cancers, but who have difficulty breathing due to tumors blocking the airway, PDT can also provide some relief from symptoms.
PDT is usually performed as a two-step outpatient procedure. During the first step of the treatment, the doctor injects a photosensitizing drug called porfimer sodium into the bloodstream. The body's cells absorb the drug, but it stays in cancer cells longer than in normal cells.
The second step of treatment occurs about 24 to 48 hours after the photosensitizer is injected. By this time, the photosensitizer will be gone from normal cells but will remain in cancer cells. The doctor will insert a thin-lighted tube, called a bronchoscope, through the mouth, down the windpipe, and into the lung. Patients will receive numbing medication during this part of the procedure so they are more comfortable.
The doctor then inserts a fiber optic cable containing a laser through the bronchoscope. The laser emits a specific wavelength of light onto the cancer tumor. As the photosensitizing drug in the tumor absorbs the light from the laser, it produces a form of oxygen that destroys the cancer cells. PDT can also help shrink or destroy cancer tumors in other ways. It can damage the tumor's blood vessels, which prevent it from receiving necessary nutrients and cause the tumor to die.
PDT is most effective in treating early-stage, non-small-cell lung cancers. The light needed to activate most photosensitizers cannot pass through more than about one centimeter of tissue. For this reason, PDT is usually used to treat small tumors in the airways of the lung. PDT can also be used to help patients breathe easier by opening up blockages of the airways caused by large tumors.
Patients who undergo PDT may still require surgery to remove new cancerous tumors at a later date since these patients are prone to develop new cancers.(Cortese DA, et al. Roentgenographically occult lung cancer. A ten-year experience. J Thorac Cardiovasc Surg. 1983 Sep;86(3):373-80).
However, in one study, 46 percent of patients with early-stage squamous cell lung cancer who underwent PDT were spared surgery (Cortese DA. Photodynamic therapy for early stage squamous cell carcinoma of the lung. Mayo Clin Proc. 1997 Jul;72(7):595-602).