Radiation oncologists have been awaiting follow-up to previous studies that suggested that radiation treatment for prostate cancer was less effective after the use of drugs to suppress hormones.
Researchers at Johns Hopkins Kimmel Cancer Center scientists say their tests provide evidence that hormone therapy will not diminish the value of radiation. Prostate cancer is a major killer of men and remains undiagnosed and can present late when the disease has spread. In this situation hormone treatment can benefit the patient as it removes one of the factors that leads to its growth.
Radical removal of prostate gland by surgery is one option but can lead to complications such as leakage of urine and impotence besides other risks of surgery. Radiation is the other non-invasive option for the cancer.
Some clinicians' concerns began five years ago when studies revealed that suppressing hormones in prostate tumors destroys tiny blood vessels that carry oxygen to cells within the tumor. But oxygen also plays a critical role in biochemical pathways that help radiation kill cancer cells by immobilizing their DNA repair process. If true, these oxygen-depleted tumors would be less likely to respond to radiation.
Theodore DeWeese, M.D., professor and chair of the Department of Radiation Oncology and Molecular Radiation Sciences at Johns Hopkins, led new tests in more than 50 rats whose prostates closely resemble human ones. "We used several rigorous tests, including a small fiberoptic probe and florescence, to detect oxygen levels in the prostate, and no rat showed any indication of low oxygen levels following hormone suppression," he says. It is still unclear as to how oxygen remains in the tumor without the small blood vessels, but DeWeese believes that clinicians can be assured that hormone therapy will not cause radiation to be less effective.
(Abstract #2399, Proceedings of the American Society for Therapeutic Radiation and Oncology, 2005)
The following news tips are based on Johns Hopkins Kimmel Cancer Center presentations made at the American Society for Therapeutic Radiation and Oncology 47th Annual Meeting October 16-20, 2005, in Denver, Colorado. For more information or to arrange interviews, contact Vanessa Wasta at 410-955-1287, [email protected]
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