Increased Radiation Doses Benefit Some Prostate Cancer Patients

For Release: November 1, 1999

INCREASED RADIATION DOSES BENEFIT HIGH-RISK GROUPS OF PROSTATE CANCER PATIENTS

Prostate cancer patients who have disease locally confined to the prostate and who have PSA levels greater than ten before treatment dramatically benefit from higher doses of radiation, a new study shows.

The randomized trial compared 149 patients who received a radiation dose of 70 Gy to 151 patients who received 78 Gy. This is the first such dose escalation trial for prostate cancer to be reported.

ìThe study showed that patients with pretreatment PSA levels greater than ten significantly benefited from receiving the higher dose,î says Alan Pollack, M.D., professor of radiation oncology at the University of Texas M.D. Anderson Cancer Center in Houston, TX. Forty-eight percent of the patients who received 70 Gy did not have rising PSA levels five years after treatment in contrast to 75 percent who received 78 Gy. ìA rising PSA profile is the most sensitive indicator that cancer has returned,î adds Dr. Pollack. The benefit of the higher dose for patients with a pretreatment PSA level greater than 10 ng/ml also was seen when the development of distant metastasis was used as the end point. The five year rate of distant metastasis was 13 percent for the 70 Gy group and two percent for the 78 Gy group, he says.

ìDose escalation to 78 Gy was achieved using conformal radiation therapy given as a boost,î says Dr. Pollack. Conformal radiation therapy uses 3D-reconstructions of the prostate to better target the tumor and spare more normal tissue.

ìWe are continuing to follow these patients,î says Dr. Pollack. At this juncture the improved outcome as a consequence of the increased dose was seen mainly in those who had pretreatment PSA levels greater than ten. ìPatients with pretreatment PSA levels less than ten may also benefit, but at this point in the study the outcome of the two dose groups was similar,î says Dr. Pollack.

Dr. Pollack concluded that, ìThere is sufficient evidence to support the implementation of dose escalation to modest levels in clinical practice for prostate cancer patients with intermediate-to-high risk features.î

Alan Pollack, M.D. presented this study on November 1 at the American Society for Therapeutic Radiology and Oncology 41st annual meeting in San Antonio, Texas.

The American Society for Therapeutic Radiology and Oncology (ASTRO) is the largest radiation oncology society in the world, with more than 5,000 members. As a leading organization in radiation oncology, biology and physics, the society's goals are to advance the scientific base of radiation therapy and to extend the benefits of radiation therapy to those with cancer.

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