The addition of two years of anti-androgen therapy (AAT) to radiation therapy reduces the risk of death caused by prostate cancer among men treated for a recurrence following a prostatectomy.
Treatment for early prostate cancer often includes the surgical removal of the prostate (prostatectomy). Unfortunately, some patients will experience a cancer recurrence following surgery.
Treatment for a recurrence following a prostatectomy may include radiation therapy and/or AAT. Since prostate cancer cells are stimulated to grow from exposure to testosterone, AAT creates anti-cancer effects by decreasing the body’s production of testosterone.
Researchers continue to explore optimal treatment combinations among men with recurrent prostate cancer to ensure optimal survival without unnecessary side effects.
Researchers of the Radiation Therapy Oncology Group (RTOG) conducted a phase III clinical trial to evaluate whether the addition of long-term AAT would improve survival among patients with prostate cancer who experienced a recurrence following initial treatment with prostatectomy alone.
This trial, RTOG 9601, included 761 patients from the United States and Canada who were treated with either two years of AAT plus radiation, or radiation only following their recurrence. Patients were followed for 12 years.
- The rate of death caused by prostate cancer was 2.3% among patients treated with AAT plus radiation, compared with 7.5% for those treated with radiation only.
- Spread of cancer to distant sites in the body occurred in 14% of patients treated with AAT plus radiation, compared with 23% of patients treated with radiation only.
- The addition of AAT did not increase the rate of severe side effects caused by radiation therapy. However, approximately 70% of men treated with AAT report swelling of the breasts, compared with only 11% of men treated with radiation therapy.
The researchers concluded that among men who experience a prostate cancer recurrence following a prostatectomy, the addition of AAT to radiation therapy decreases the risk of death from prostate cancer in addition to decreasing the risk of cancer spread compared to radiation therapy only.
Subgroup analysis is ongoing to determine if certain groups of patients derive greater benefit from AAT than others.
Reference: Shipley W, et al. Report of NRG Oncology/RTOG 9601, a phase III trial in prostate cancer: Anti-androgen therapy (AAT) with bicalutamide during and after radiation therapy (RT) in patients following radical prostatectomy (RP) with pT2-3pN0 disease and an elevated PSA. Proceedings from the 57th annual ASTRO meeting. Presented October 19, 2015. Available at: https://www.astro.org/News-and-Media/News-Releases/2015/Shipley_AM15.aspx. Accessed October 23, 2015.