Photodynamic therapy is a non-invasive treatment for esophageal and non-small cell lung cancer that precisely targets cancer cells without damaging healthy cells and without severe side effects. Photodynamic therapy can be used in conjunction with other surgery, chemotherapy and radiation therapy. Or it may be the appropriate therapy when a patient cannot have surgery. Photodynamic therapy uses a drug that is light-sensitive, called a photosensitizer, and a particular type of light delivered by a laser. When the photosensitizer drug is exposed to a specific wavelength of light, the drugs produce a form of oxygen that kills the cancer cells in the tumor where the light has been targeted.
How does photodynamic therapy work?
Photodynamic therapy is a two part process that uses a combination of drugs and lasers. The first step of the procedure involves injection of the photosensitizing drug, porfimer sodium, into the bloodstream. The drug is absorbed by cells all over the body, but stays in cancer cells longer than in normal cells. Approximately 24 to 72 hours after injection, when the photosensitizer drug has left normal cells but remains in cancer cells, the tumor is exposed to light. The photosensitizer in the tumor absorbs the light and produces an active form of oxygen that destroys the nearby cancer cells.
In addition to directly killing the cancer cells, photodynamic therapy shrinks or destroys tumors in two other ways: the photosensitizer drug can damage blood vessels in the tumor, therapy preventing the cancer cells from receiving necessary nutrients and photodynamic therapy may activate the immune system to attack tumor cells. The light used in photodynamic therapy can come from a laser inserted through an endoscope, a think lighted tube that allows the physician to view images inside the body – in the lungs or esophagus. Other light sources include light-emitting diodes, as are used in treating surface tumors such as skin cancer. Photodynamic therapy can be used alone or in conjunction with surgery, radiation and chemotherapy. It has few apparent long-term side effects and is currently being investigated for potential immunologic effects.
What types of cancer are treated by photodynamic therapy?
Photodynamic therapy is approved to treat and relieve the symptoms of:
- Cancer of the esophagus – when the tumor totally blocks the esophagus or partly blocks the esophagus and cannot be treated by laser alone
- Barrett's Esophagus – when there are precancerous lesions that may lead to esophageal cancer, this is the best therapy when surgery cannot be performed
- Non-small cell lung cancer that affects the lining of the large breathing tubes called the bronchi. This type of cancer is called endobronchial cancer
- It has also been used to treat early, localized gastric carcinoma, superficial basal cell carcinomas, superficial oral and laryngeal tumors, as an adjunct to stenting for inoperable cholangiocarcinomas, and as part of lung-sparing surgery for mesothelioma
Dr. Patrick Ross talks photodynamic therapy to treat lung cancer
[Dr. Ross video]