Men who underwent radiotherapy for localized high-risk prostate cancer and had 18 months of androgen blockade did just as well as comparable men who had 3 years of androgen blockade.
The finding of nearly identical overall and disease-free survival with traditional and shortened hormone therapy is "practice changing," Dr. Bruce Roth said during a press briefing at the 2013 Genitourinary Cancers Symposium.
Dr. Bruce Roth
"I would be willing to change the way I treat my patients," based on the results of the phase III study, said Dr. Roth of Washington University, St. Louis. "The consequences of long-term androgen deprivation are often more striking than the positive aspects of prolonging it. If treatment time can be safely halved, patients will enjoy a much better quality of life."
Dr. Abdenour Nabid of the Centre Hospitalier Universitaire de Sherbrooke, Canada, headed the study. It randomized 630 men with node-negative high-risk prostate cancer to radiation therapy plus either 36 or 18 months of androgen blockade. The hormone therapy consisted of bicalutamide 50 mg/day for 1 month plus goserelin 10.8 mg given as an injection once every 3 months.
At baseline, the patients were a median of 71 years old; the median prostate specific antigen (PSA) level was 16 ng/mL, and the median Gleason score was 8. Most had T2-T3 disease.
The median follow-up period was about 77 months. At that point, 23% of patients in the extended therapy group and 24% in the abbreviated therapy group had died. Of these 147 patients, 116 (79%) had died from causes other than prostate cancer.
Fifty patients developed bone metastases, Dr. Nabid said, but there was not a significant between-group difference in this outcome. Nor were there differences in biochemical failure, regional or distant recurrence, pelvic metastases, or the need for a second course of androgen blockade.
When Dr. Nabid broke the data out by 5- and 10-year follow-up points, the survival results were similar. At 5 years, overall survival was 92% in the 36-month group and 87% in the 18-month group; disease specific survival was 98% and 96%, respectively. At 10 years, overall survival was 64% vs. 63%, and disease-specific survival was 87% in both groups.
He said the study will follow all patients through 10 years, adding "I am convinced this finding won’t change."
Decreasing the length of androgen blockade could avoid some cases of permanent castration syndrome, Dr. Roth said. "The longer the hormone therapy, the less chance that testosterone will recover when it’s finished. With 3 years of hormone therapy, you might be inducing a lifetime of hormone suppression" and a host of problems including sexual dysfunction, loss of muscle tone, and increased visceral fat. These consequences are in turn associated with significantly increased rates of metabolic syndrome, diabetes, myocardial infarction, and coronary heart disease.
"If a patient has several decades left of life and his testosterone levels are lowered to the point of castration syndrome, there is a price to pay," Dr. Roth said. "If this patient dies of a heart attack 10 years before he would have died of prostate cancer, we have not really provided good anticancer therapy."
This is the first study showing that short-term androgen blockade is both safe and effective. "Could we get by with less?" Dr. Nabid asked. "We don’t know. Previous trials have shown that 6 months of hormone treatment is inferior to 24 months, but we don’t know what the effect of 12 months would be. Still, we are excited to see this, and our hope is that this will change the standard of care for this stage of disease."
Dr. Nabid had no financial disclosures.