Antiandrogen therapy enhances outcomes of salvage radiation

Two years of antiandrogen therapy improved survival in patients treated with salvage radiation. This report represents an update with over 12 years of median follow up. The results with 7 years of follow-up were previously reported here.

The results of the randomized clinical trial RTOG 96-01 were presented by Shipley et al. at the recent ASTRO meeting and reported in a press release. Between 1998 and 2003, 761 patients were treated at multiple sites across the US and Canada. All patients had biochemical recurrence and either stage pT2 with a positive margin or stage pT3, without lymph node involvement or metastases. All patients received 64.6 Gy of EBRT in 1.8 Gy increments (36 fractions), and either 24 months of bicalutamide (150 mg) or a placebo. After 12.6 years median follow up, the antiandrogen had the following effects:

• ·      Reduced tumor progression and the incidence of local re-growth
• ·      Reduced rate of metastases from 23% to 14%
• ·      Reduced death from PC from 7.5% to 2.3%
• ·      Improved overall survival at 10 years from 78% to 82% (p=.04)
• ·      GI or GU toxicity were low and similar in both arms.
• ·      Gynecomastia was common with bicalutamide.

While the salvage radiation dose delivered in this study falls short of the 70 Gy now considered adequate, it does provide evidence of a survival benefit linked to added hormone therapy. Another randomized clinical trial, GETUG AFU-16, proved that even a short course of ADT significantly improved progression free survival when used with salvage radiation, but longer follow up will be necessary to prove a benefit in prostate cancer survival. RTOG 96-01 proves that prostate cancer specific survival is indeed improved by the combination of hormone therapy with salvage radiation, although the benefit may be limited to those with lower PSA and negative margins.