HORMONE TREATMENTS BEFORE RADIATION NOW CONSIDERED EFFECTIVE
-Mouse Studies Quell Worries from Previous Prostate Cancer Study
Radiation oncologists have eagerly anticipated a follow-up to previous studies that implied radiation treatment for prostate cancer was less effective after the use of drugs to suppress hormones. Now, Johns Hopkins Kimmel Cancer Center scientists say their tests provide evidence that hormone therapy will not diminish the value of radiation.
The root of 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.