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Addition of both androgen suppression therapy, external-beam radiation to brachytherapy decreases prostate cancer-specific mortality in men with high-risk disease, study shows

Thursday, August 20 2009 | Comments

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What's This? In with men with high-risk prostate cancer, the combined use of both supplemental androgen suppression therapy (AST) and external beam radiation (EBRT) with brachytherapy as compared with brachytherapy alone is associated with a decreased risk of prostate cancer-specific mortality, according to study results. However, supplementation with either AST or EBRT alone does not appear to confer a survival advantage.

Studies have shown that adding AST to EBRT prolongs survival, compared with radiation therapy alone, in men with localized high-risk and locally advanced prostate cancer, but studies examining the use of AST and EBRT with brachytherapy are lacking, the authors explained.

To remedy this omission, researchers examined a cohort of 1,342 men who were treated with brachytherapy for localized or locally advanced prostate cancer. They performed competing risks multivariable regression to estimate the risk of prostate-cancer specific mortality in men treated with brachytherapy alone or with supplemental AST, EBRT, or both, adjusting for age, year of treatment, and known prostate cancer prognostic factors.

Results showed that 16% of the men received brachytherapy alone, 19% received supplemental AST, 16% received supplemental EBRT, and 48% received both AST and EBRT in addition to brachytherapy. The men who received both of the supplemental treatments had worse baseline prognostic factors, including being more likely to have palpable localized or locally advanced disease (P<.001), Gleason scores of 7 to 10 (P<.001), and all 3 factors indicative of high risk (advanced clinical stage, PSA>20 ng/mL, and Gleason score 8-10; P<.001) as compared with the men who were treated with brachytherapy alone or with only one of the supplemental treatments.

Even with the higher baseline probabilities of prostate-cancer specific mortality at baseline, the risk of death from prostate cancer after a median follow-up of 5.1 years was significantly reduced in the men treated with brachytherapy and both supplemental treatments as compared with those who received neither of the supplemental treatments (adjusted hazard ratio, 0.32; 95% CI, 0.14-0.73; P=.006).

There was a trend toward a reduction in all-cause mortality in the group that received the trimodal treatment, but it did not reach statistical significance.

The addition of either AST or ERBT alone to brachytherapy did not lead to a significant reduction in prostate-cancer specific mortality.

"These data should heighten awareness among physicians that, to maximize curability in men with high-risk prostate cancer treated using brachytherapy, the addition of both supplemental AST and ERBT to brachytherapy seems necessary," the authors concluded.

The study was published online ahead of print July 13 in the Journal of Clinical Oncology by D'Amico A, et al.

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