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BookmarkScienceDaily (Aug. 5, 2004) — Philadelphia, PA -- A new study that appears in the June 2004 issue of the Journal of Clinical Oncology shows that the life-expectancy of patients with advanced stage lung cancer can be extended with the use of photodynamic therapy, or PDT, in addition to surgical intervention. Typically, advanced stage non-small cell lung cancer patients have a median survival of 6-9 months when treated with the current standard of care, chemotherapy alone. However, this same set of patients demonstrated a median survival of more than 22 months when chemotherapy was combined with surgery and intraoperative PDT, a new laser-based cancer treatment. Joseph S. Friedberg, MD, Chief of Thoracic Surgery at Presbyterian-University of Pennsylvania Medical Center, Stephen Hahn, MD, Clinical Associate Professor of Radiation Therapy and James P. Stevenson, MD, Assistant Professor of Medicine are the co-investigators in this trial at the University of Pennsylvania Medical Center.
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“We consider these results preliminary but extremely encouraging. We expected PDT to make a difference in the rate of local recurrence and it has,” says Dr. Friedberg, “However, we did not anticipate the dramatic increase in survival that we have observed. In addition to the local control, there must be some sort of systemic immune response that is contributing to the enhanced survival we are observing in these patients with a very advanced form of the disease. We are exploring this phenomenon at a number of levels and feel we may have stumbled upon the makings of a new immunologic approach to treating patients with all stages of lung cancer. It is an area of research about which we are very excited and actively pursuing.”
In PDT, a nontoxic photosensitizing agent, Photofrin, is injected into the blood stream and concentrates in cancer cells, allowing the cancer to become very sensitive to light. Using a laser to shine light on these cells results in a very effective mechanism for killing cancer cells. The damage occurs only where the light is shined, limiting the harm to healthy tissue. PDT has rarely been used in this way, combining it with other treatment modalities, although it has been used by clinicians for treating small, easily visualized tumors in the windpipe and esophagus. Patients eligible for the treatment are those whose cancer has spread within the chest cavity.
In the study, each patient is treated with chemotherapy until the cancer stops responding, the normal course for this disease and the limitation of chemotherapy alone. After it is confirmed that the cancer has not spread beyond the chest cavity, the patient then receives Photofrin 24 hours prior to surgery. During surgery, the cancer is removed, which may involve excising all or part of the affected lung. Then, surgeons shine a laser into the chest cavity, giving the appropriate dose of light in an effort to kill any remaining microscopic tumor cells that remain after surgery.
It is known that surgery, without PDT, will almost certainly be accompanied by a high rate of local recurrence, likely a result of the invisible remaining disease being targeted with PDT. The treatment has proven very safe, largely as a function of using a specially designed computer system to measure and monitor the amount of laser light delivered at the time of treatment.
