ADT for Intermediate-Risk Prostate Cancer Does Not Appear to Improve Overall Survival

TON - March/April 2011, VOL 4, NO 2 — April 11, 2011

Adding androgen-deprivation therapy (ADT) to dose-escalated external beam radiotherapy (EBRT) for men with intermediate-risk prostate cancer improves biochemical failure-free survival but not overall survival (OS), according to a retrospective study. Researchers from Emory University School of Medicine and the Atlanta Veterans Administration in Georgia conducted the study. Although previous trials have found that combining ADT with EBRT improves biochemical failure-free survival and OS in men with high-risk prostate cancer, the dual therapy has never been thoroughly investigated in men with intermediaterisk disease.

Using a database of 850 men treated at multiple institutions, investigators identified 251 with intermediate-risk prostate cancer, which they defined as stage ≥T2b disease or a prostate-specific antigen (PSA) level >10 ng/mL or a Gleason score (GS) of 7. Patients meeting any of the following criteria were excluded: stage ≥T3 disease, PSA level >20 ng/mL, GS ≥8, positive nodes, or distant metastases. All patients in the study had received EBRT to a dose ≥70 Gy but none had undergone brachytherapy or prostatectomy; 87 were given ADT. Mean PSA score was higher for men in the ADT group than for those in the EBRT-only arm (12.0 ng/mL vs 8.9 ng/mL, respectively), and more men in the ADT group than the EBRT-only arm underwent pelvic radiography (49% vs 22%, respectively). The study arms were well balanced in terms of age, race, mean EBRT dose, and the proportion of patients who had intensity-modulated radiation therapy (IMRT). Median follow- up was 47 months.

The 5-year rate of biochemical failurefree survival was 80% for the ADT group compared with 76% for the EBRT-only group (P = .017). At 5 years, 84% of patients in the ADT group were alive compared with 76% of patients not given ADT (P = .028). Multi variate analyses found that ADT use and GS were the only significant independent predictors of biochemical failure-free survival and that PSA level and IMRT were the only significant independent predictors of OS. Adding ADT to EBRT did not increase the incidence or severity of gastrointestinal and genitourinary toxicities. In an interview with The Oncology Nurse-APN/PA, lead investigator Scott Edelman, MD, assistant professor of radiation oncology at Emory University, said although the data support nurses counseling their patients with intermediate-risk prostate cancer that “if you take hormonal therapy [for 6 months], there is a really good chance that 3 or 4 years down the road, your PSA will be under control,” it is premature to suggest adding ADT improves survival. Edelman said the findings might reassure some men contemplating it, but they need to know about the significant side effects associated with the therapy before deciding on treatment.

“Hormonal therapy gives you hot flashes and breast tenderness. It may give you a little breast enlargement and may make you more emotional. It also may take away your sex drive in the short term and give you problems with erections, and increase your risk for osteoporosis and bone fractures,” he explained.

Edelman said it comes down to what matters most to the patient. “If the patient is someone who wants a cure— based on his PSA level—and that is the most important thing for him, then he should go on hormonal therapy. However, if quality of life is the most important issue, then it would probably be best to tell them not to go on hormonal therapy.” A randomized trial is currently investigating combination therapy in men with intermediate-risk prostate cancer

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