Photodynamic therapy, or PDT, has been performed on lung cancer patients since 1980. The United States Food and Drug Administration approved PDT for the treatment of certain types of lung cancer in the latter 1990s. The Cancer Treatment Centers of America reports that PDT is more than 90 percent effective in treating esophageal and early-stage lung cancers (See Reference 2).
Photodynamic Therapy
During the procedure of PDT, a person is injected with a light-activated drug, such as Photofrin. This drug accumulates in cancer cells. After a period of 24 or 48 hours, an endoscope containing a laser light is inserted to where the tumor lies. The light activates the drug, which kills the cancer cells. The National Cancer Institute, or NCI, says that PDT also destroys blood vessels that supply the tumor with nutrients and oxygen and may activate the immune system to attack tumor cells (See Resource 1).
Benefits
The Cancer Treatment Centers of America report that PDT has many benefits. It is an outpatient procedure, it requires minimal use of anesthesia, it is of less risk than surgical procedures and it produces few side effects (See Reference 2). Additionally, it can be performed multiple times without the buildup of toxicity, and it can be used on tumors where surgery is complicated or not feasible.
Limitations
Currently, PDT only works on tumors that can be accessed by an endoscope, which is the flexible tube that shines a light on the tumor. An article posted by the Oregon Medical Laser Center says that devices that implant optical fibers are in development (See Reference 1). Also, this source says red light penetrates more deeply than other wavelengths of light and is being used to extend the usefulness of PDT.
Efficacy
The results of a phase II clinical trial published in a 1992 issue of the "Journal of Clinical Oncology" reported that PDT demonstrated a complete response in 50 of 59 patients with lung carcinomas (See Reference 4). A study in a 2003 issue of "Lung Cancer" reported that in a phase II clinical trial the newer generation photosensitive drug, NPe6, produced a complete response in 83 percent of patients with squamous cell carcinoma of the lung (See Reference 5). This drug also produced less photosensitivity side effects than Photofrin.
Side Effects
The most common side effect of PDT is light sensitivity. The light-sensitive drug Photofrin does not degrade for 4 to 6 weeks, and during this time, a patient is sensitive to sunlight and other bright lights. Gradually, the drug disappears as well as the photosensitivity. Some patients experience pain from inflammation that occurs at the site of tumor breakdown. Also, because of fluid buildup in the lungs, a person may become short of breath.
References
- Oregon Medical Laser Center: Information for Patients: Photodynamic Therapy of Lung Cancer
- Cancer Treatment Centers of America: Photodynamic Therapy
- Journal of Thoracic Oncology: Photodynamic Therapy (PDT) for Lung Cancers
- PubMed: A Prospective Phase II Study on Photodynamic Therapy with Photofrin II for Centrally Located Early-stage Lung Cancer
- PubMed: Phase II Clinical Study of Photodynamic Therapy Using Mono-L-aspartyl Chlorin e6 and Diode Laser
