ATLANTA—Long-term androgen deprivation therapy after radiation treatment for intermediate-risk prostate cancer (PCa) does not improve disease-specific or overall survival, according to a new study presented at the American Society for Radiation Oncology’s 55th annual meeting.
Researchers came to this conclusion based on a secondary analysis of the RTOG 9202 trial. The trial evaluated the potential benefits of long-term adjuvant androgen deprivation (LTAD) for two years after initial androgen deprivation compared with short-term (initial) androgen deprivation (STAD) in mostly high-risk PCa patients receiving external beam radiation therapy. Because some intermediate-risk PCa patients were included in the study, the current analysis was conducted to determine if patients in the intermediate-risk subset experienced an additional survival benefit with LTAD.
“Most clinicians have felt that ‘more was better’ when it came to blocking testosterone in prostate cancer patients; however, results for the specific endpoints we focused on, overall survival and disease-specific survival, indicate that this was clearly not the case,” said lead author Amin Mirhadi, MD, a radiation oncologist at Cedars-Sinai Medical Center in Los Angeles. “These data support administering less treatment, which will result in fewer side effects and reduce patients’ overall healthcare costs.”
Dr. Mirhadi and his colleagues reviewed data from 133 men enrolled in RTOG 9202 categorized as having intermediate-risk PCa. The investigators defined this in two ways: T2 disease, a PSA level less than 10 ng/mL, and a Gleason Score of 7, or T2 disease, a PSA level of 10-20, and a Gleason score less than 7.
The LTAD group consisted of 59 patients, and the STAD group consisted of 74 patients. The median follow-up was more than 11 years. The study revealed no significant difference in overall survival, with 10-year estimates of 61% for the STAD group and 65% for the LTAD group. Disease-specific survival rates were 96% in both groups. The 10-year PSA failure rates were 53% for the STAD group and 55% for the LTAD group.
“We were surprised by the findings. We thought the more hormones the better,” Dr. Mirhadi told Renal & Urology News. “But until now no one has looked at the question is two years really that much more incrementally beneficial for intermediate-risk prostate cancer.”
The results of this secondary analysis should be of particular interest to urologists, he said. Many urologists and radiation oncologists like to use long-term hormone treatment for men with intermediate-risk PCa, but the data show that four months is all that is required for intermediate-risk disease, Dr. Mirhadi said.
The new findings could translate into an improved quality of life for patients with intermediate-risk PCa, he said. The adverse effects of four months of androgen suppression therapy are almost always reversible, but this is not the case when patients receive up to two years of androgen suppression therapy, he said. “It often puts men at much greater risk for bone loss, hip fracture and other complications,” he said.