Continuation of androgen deprivation therapy for an additional 24 months improves all disease end points during 15 years of follow-up compared with short-term androgen deprivation in men with locally advanced prostate cancer treated with radiotherapy. This is the conclusion from the final report of the RTOG 9202 trial.
The study was presented at the American Society for Radiation Oncology (ASTRO) 57th Annual Meeting.
Asked to comment on the study, David Beyer, MD, from the University of Arizona, in Tuscon, and president-elect of ASTRO, said that on the basis of RTOG 9290 results, long-term androgen deprivation therapy is the standard of care.
"As long as we select the right patient — and the study was in locally advanced prostate cancer — long-term androgen deprivation should be the standard of care," he said.
"One of the questions that patients always want to know the answer to is, 'Am I going to die of this cancer?' " trial investigator Colleen Lawton, MD, vice-chair, Department of Radiation Oncology, Medical College of Wisconsin, in Milwaukee, said during a press briefing.
"And the answer from this trial is, if you've had long-term hormone therapy, we can reduce that chance significantly."
The RTOG 9202 study was a randomized, multi-institution study involving 1554 patients with stage T2C to T4 prostate cancer.
"Patients could not have any extra pelvic lymph node involvement," Dr Lawton said.
"And their PSA [prostate specific antigen level] had to be less than 150 ng/mL at study entry."
In addition, the patients had received no prior chemotherapy or hormone therapy.
Patients were randomly assigned to receive 4 months of goserelin (Zoladex, AstraZeneca Pharmaceuticals LP) and flutamide (Eulexin, Schering-Plough Corporation) beginning 2 months prior to receiving radiation therapy (short-term androgen deprivation) or the same short-term androgen deprivation regimen followed by an additional 24 months of goserelin after completion of the radiation protocol (long-term androgen deprivation).
Radiation therapy was delivered at a dose of 44 Gy to 46 Gy to the pelvic nodes and in doses of 65 Gy to 70 Gy to the prostate.
The median follow-up period for 1520-protocol-eligible patients was 19.6 years.
At 15 years, the group receiving long-term androgen deprivation therapy continued to show favorable outcomes compared with the group undergoing short-term androgen deprivation.
Table. Outcomes at 15 Years of Follow-up After Radiation Therapy
| Long-term Androgen Therapy | Short-term Androgen Therapy | Hazard Ratio; P-value | |
| Disease-free survival | 16% | 10% | HR = 72; P < .001 |
| PSA failure (cumulative incidence) | 45% | 61% | HR = 0.57; P < .0001 |
| Local progression | 13% | 23% | HR = 0.53; P < .0001 |
| Distant metastases | 17% | 26% | HR = 0.61; P < .0001 |
| Disease-specific survival | 84% | 78% | HR = 0.67; P = .002 |
| Overall survival | 30% | 27% | HR = 0.90; P = .12 |
Furthermore, for a subgroup of 337 patients with a Gleason score of 8 to 10 at study outset, all disease-specific end points strongly favored long-term androgen deprivation, with a trend toward better overall survival, at 21%, for the long-term group vs 17% for the short-term group, investigators observe.
"Our findings reinforce the benefit of longer androgen deprivation therapy for patients with locally advanced prostate cancer," Dr Lawton said.
"More patients with advanced prostate cancer should be considered for and may benefit from long-term androgen deprivation," she said.
The study was supported by the National Cancer Institute.
American Society for Radiation Oncology (ASTRO) 57th Annual Meeting: Abstract 97. Presented October 19, 2015.
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