Androgen Blockade and Salvage Radiation Therapy in Prostate Cancer: Cautious Optimism Amid Unanswered Questions
The recent report of results of RTOG 9601 by Shipley et al in The New England Journal of Medicine—reviewed in this issue of The ASCO Post—strongly supports the variably used practice of adding “androgen blockade” to salvage radiation therapy in men with a rising prostate-specific antigen (PSA) after radical prostatectomy. The findings show a clear reduction in prostate cancer–specific and overall mortality with the addition of 2 years of bicalutamide to salvage radiation therapy. Another likely (although not demonstrated) benefit is the reduction in the need to treat patients with subsequent life-long continuous or intermittent androgen blockade at the expense of treating all men with 2 years of bicalutamide.RTOG 9601’s results further strengthen the growing concept that inhibition of androgen signaling can work in synergy with radiotherapy by inhibiting DNA repair and functioning as a potent radiosensitizer.These data are consistent with the large number of trials in intermediate- and high-risk localized prostate cancer in which the addition of androgen suppression to radiotherapy improved overall survival. However, one should be cautious about extrapolating all methods of androgen blockade as equal, as one of the only trials of radiotherapy in localized prostate cancer that did not show a benefit from androgen blockade was when bicalutamide monotherapy was used.
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