Shortened Hormone Therapy Course Feasible for High-Risk Prostate Cancer

Abdenour Nabid, MD

Shortening the course of androgen blockade (AB) therapy from 36 months to 18 months when combined with radiation therapy does not appear to compromise outcomes in patients with high-risk prostate cancer, according to results of a randomized, multicenter, Phase III study reported at the 4th Annual Genitourinary Symposium held February 14-16, 2013 in Orlando, Florida.

The study found that both overall survival (OS) and disease-specific survival (DSS) were similar in patients who received 36 or 18 months of treatment.

Hormone therapy is associated with uncomfortable and disturbing side effects that negatively impact quality of life. These include hot flashes, decreased libido, impotence, and fatigue, which are among a group of symptoms known as the “castration syndrome.” The ability to treat high-risk disease with a shorter course of hormone therapy could have a major impact on quality of life for these patients.

“A long list of side effects makes the lives of most of our patients quite miserable,” commented lead author Abdenour Nabid, MD, associate professor at Centre Hospitalier de Universitaire de Sherbrooke in Sherbrooke, Canada. “A shorter course could reduce the quantity and intensity of its unpleasant side effects as well as treatment costs. We hope these results will convince doctors that they can stop hormone therapy after 1.5 years instead of 2 to 3 years.”

The study enrolled 630 patients with node-negative, high-risk prostate cancer treated with radiotherapy to the pelvic area and prostate bed. They were randomized to either 36 months ( n = 310) or 18 months (n = 320) of AB therapy (bicalutamide 50 mg for 1 month plus goserelin 10.8 mg every 3 months) given before, during, and after radiation.

Patient characteristics were well balanced between the two arms, with a median age of 71 years, median PSA of >20 ng/mL, and a median Gleason score of >7. The majority of patients had stage T3-4 disease.

At a median follow-up of 77 months, the two groups had no significant difference in biochemical failure, metastasis, bone-only metastasis, and cause of death. Mortality rates were 22.9% (71 patients) in the longer-duration hormone therapy arm versus 23.8% (76 patients) in the shorter-duration arm. Of 147 deaths, 116 were deemed unrelated to prostate cancer.

Five-year OS was 92.1% in the longer-duration arm versus 86.8% in the shorter-duration arm, and 10-year OS was 63.6% versus 63.2%, respectively. Five-year DSS was 97.6% and 96.4%, respectively, and 10-year DSS rates were 87.2% in both arms.

The main cause of death was second cancer (7.3% of patients); 4.9% died of prostate cancer, and 4.4% of cardiovascular disease.

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“In localized prostate cancer patients treated with radiation therapy and androgen blockade, treatment with 18 months of androgen blockade is safe. This could represent a threshold for no further gain,” noted Nabid.

“This study could change the standard of care from 36 months to at least 24 months and perhaps 18 months, if the full, peer-reviewed publication bears these findings out,” said Bruce Roth, MD, Professor, Department of Medicine, Washington University, St Louis, Missouri, who moderated a press briefing February 12 where the findings were presented.

Nabid A, Carrier N, Martin AG, et al. High-risk prostate cancer treated with pelvic radiotherapy and 36 versus 18 months of androgen blockade: results of a phase III randomized study. Presented at: 4th Annual Genitourinary Cancer Symposium; February 14-16, 2013; Orlando, FL. Abstract 3.

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