PHILADELPHIA, PA USA (News Release) - September 26, 2013 - Men with prostate cancer who are at intermediate risk for cancer recurrence after initial treatment are best served with a standard 8-week course of hormonal therapy (HT), followed by radiotherapy (RT) with an 8 additional weeks of HT, according to results of a Radiation Therapy Oncology Group (RTOG) trial reported today at the American Society for Radiation Oncology (ASTRO) 55th Annual Meeting. RTOG 9910 evaluated whether extending the course of HT to 28 weeks prior to RT plus 8 additional weeks of HT improved patient outcomes. The study results showed no additional benefit to patients with the extended course of HT. The goal of HT (also called androgen-deprivation therapy or androgen-suppression therapy) is to reduce levels of male hormones (or androgens) in the body that stimulate prostate cancer cell growth.
| “This study provides definitive evidence that more treatment is not necessarily better treatment for these patients,” says Thomas M. Pisansky, M.D., principal investigator for the RTOG 9910 phase III multicenter trial, and professor of radiation oncology at the Mayo Clinic in Rochester, MN |
“This study provides definitive evidence that more treatment is not necessarily better treatment for these patients,” says Thomas M. Pisansky, M.D., principal investigator for the RTOG 9910 phase III multicenter trial, and professor of radiation oncology at the Mayo Clinic in Rochester, MN. Despite practice trends to increase the duration of hormonal therapy, this evidence demonstrates that a short 16-week course of hormonal therapy provides excellent outcomes for patients with intermediate-risk prostate cancer without the increased side effects of longer hormonal therapy that may include hot flashes and erectile dysfunction. It’s also excellent news that we can reduce the cost of the medical therapy and yet not sacrifice patient outcomes.” More than 230 000 men are expected to be diagnosed with prostate cancer in 2013, and one-third or more are likely to be at intermediate risk for cancer recurrence.
Nearly 1 580 study participants with intermediate-risk prostate cancer were enrolled in the RTOG 9910 trial at 152 academic and community-based research sites to test whether extended HT prior to RT would reduce disease-related deaths based upon prior RTOG research, preliminary animal research, and observation in surgical patients demonstrating that extended HT resulted in smaller amounts of residual cancer at the time of surgery. The participants were evenly randomized to receive a 16-week total course of HT (Arm 1) or a 36-week course of HT (Arm 2).
At 10 years of follow-up, prostate cancer deaths among participants numbered 30 in Arm 1 (a 95 percent disease-specific survival (DSS) rate) and 24 in Arm 2 (a 96 percent DSS rate). Dr. Pisansky reported that far fewer participants died of prostate cancer than projected at the time of study design (3% prostate cancer mortality at eight years vs. 21% expected). Given the lower death rate from prostate cancer, a much larger trial of more than 7,000 study participants would be required to determine adequately if the longer course of HT reduced the risk of prostate cancer death—an enrollment goal he emphasized would be extremely difficult to achieve. However, Dr. Pisansky also reported that the shorter course of HT was substantiated as the optimal treatment regimen by the many other end points evaluated in the study. These included, at 10 years, comparisons of participants in Arm 1 and Arm 2 overall survival (66 percent vs. 67 percent), incidence of a rising prostate-specific antigen (PSA) level (27 percent in both Arms), locoregional prostate cancer recurrence (6 percent vs. 4 percent), and cancer metastasis rates (6 percent in both Arms). “The results across all end points are so close that this study confirms we have a treatment that works very, very well,” says Dr. Pisansky.
Dr. Pisansky also noted that the RTOG 9910 trial results substantiate those of the phase III RTOG 9408 trial published in the New England Journal of Medicine that compared a 16-week HT plus RT regimen (the control arm of RTOG 9910) against RT with no HT. “In the RTOG 9408 trial, men with intermediate-risk prostate cancer at 10 years post treatment had a disease-specific survival rate of 97 percent, and in 9910 we observed a very similar outcome—essentially reproducing the 9408 results, and providing greater confidence that the results of 9408 are reproducible,” points out Dr. Pisansky.
“The work RTOG investigators have produced in the area of prostate cancer treatment has made a significant contribution to the understanding of optimal treatment options for patients. I congratulate Dr. Pisansky and all those who have worked diligently on this trial over the years to bring forward these important results,” says Walter J. Curran, Jr, M.D., RTOG Group Chairman and Executive Director of the Winship Cancer Institute of Emory University in Atlanta.
Based upon preliminary research and eliminating patients with “low” or “very-high” cancer recurrence risks, RTOG 9910 identified study participants at intermediate risk for disease recurrence by using any of the following combinations:
- Clinical stage T1b-4, Gleason score 2-6, and PSA> 10 but ≤ 100
- Clinical stage T1b-4, Gleason score 7, and PSA < 20
- Clinical stage T1b-1c, Gleason score 8-10, and PSA < 20
[ NEWS RELEASE ]
