A research has found that a shorter course of androgen suppression therapy prior to radiation therapy, when compared to a longer course of androgen suppression therapy, yields favorable outcomes and fewer adverse effects for intermediate-risk prostate cancer patients. The research was presented at the American Society for Radiation Oncology's (ASTRO) 55th Annual Meeting. The study confirmed a disease-specific-survival (DSS) rate of 95 percent when patients received fewer weeks of neoadjuvant (NEO) total androgen suppression (TAS).
The multi-institutional phase III trial, Radiation Therapy Oncology Group (RTOG) 9910, evaluated 1,490 intermediate-risk prostate cancer (PCa) patients from 152 institutions in the U.S. and Canada. Patients were accrued from 2000 to 2004 and followed for an average of 9 years, and the average age of the men was 71 at the time of accrual. The patients were stratified and randomized into two groups―Group 1 consisted of 752 patients who received eight weeks of NEO TAS, and Group 2 consisted of 738 patients who received 28 weeks of NEO TAS. Both groups then received eight weeks of external beam radiation therapy (RT) and concurrent TAS.
Cumulative incidence was used to estimate and test efficacy for DSS, prostate-specific antigen (PSA) failure, locoregional tumor progression and distant metastasis. Overall survival (OS) rates were estimated via the Kaplan-Meier method and efficacy tested with log rank. There were 30 PCa deaths in Group 1, for a 10-year DSS rate of 95 percent; and 24 PCa deaths in Group 2, for a 10-year DSS rate of 96 percent (no statistical difference). There were 200 additional deaths not attributable to PCa in Group 1 for a 10-year OS rate of 66 percent, and 196 such deaths in Group 2, for a 10-year OS rate of 67 percent. By 10 years, 27 percent of patients had a PSA failure (using the newer RTOG-ASTRO definition of nadir+2), 5 percent had PCa recurrence in the prostate (locoregional) and 6 percent had distant metastasis. Hot flashes and erectile dysfunction were more common in Group 2.