USE ENDOCRINE THERAPY WITH RADIOTHERAPY FOR INTERMDIATE RISK PROSTATE CANCER

Effect of short-term endocrine therapy prior to and during radiation therapy on overall survival in patients with T1b-T2b adenocarcinoma of the prostate and PSA equal to or less than 20

09.03.10

Category: Scientific News

Initial results of RTOG 94-08 study

A large phase III Radiation Therapy Oncology Group (RTOG) study reports that men with intermediate-risk, early-stage prostate cancer (early-stage disease that is likely to recur) who undergo short-term hormone therapy before and during moderate-dose radiation therapy live longer and are less likely to experience a recurrence, compared with men who receive the same radiation therapy alone. However, the addition of short-term hormone therapy does not appear to confer the same benefit to men with low-risk, early-stage disease.

"These data indicate that men with early-stage prostate cancer who have intermediate-risk disease stand to benefit from the addition of four months of hormone therapy prior to and during radiation therapy," said study author Dr Christopher Jones, a partner of Radiological Associates of Sacramento who serves as their principal investigator for RTOG. The results were presented at the 2010 Genitourinary Cancer Symposium (San Francisco, 5-7 March 2010), the event co-sponsored by the American Society for Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO) and the Society of Urologic Oncology (SUO).

In this study, researchers compared overall survival and recurrence (as determined by repeat prostate biopsies) in 987 men with localized prostate cancer who had a PSA of 20 or less and who received four months of hormone therapy (HRT), starting two months before radiation therapy, and 992 similar men who received radiation therapy alone (the standard treatment).

After a median follow-up of 8.4 years in the HRT group and 8.1 years in the radiation-only group, the study met its primary endpoint by documenting that 51% of the patients who received HRT were still alive at 12 years, compared with 46% of those who received radiation alone. The survival benefit of hormone therapy appeared to be greatest among men with intermediate-risk disease (a Gleason Score of 7, or a Gleason Score of 6 or less with either a PSA between 10 and 20 or clinical T2b disease); 54% of patients in this study had this stage of disease. Investigators found that men with low-risk disease (35% of participants) did not benefit from the addition of hormone therapy. Analysis of secondary endpoints and risk-stratified subsets continues to help identify those patients who benefit most from androgen suppression.

At two years following treatment, 843 men underwent repeat prostate biopsies. In those treated with hormones and radiation, 78% of these biopsies showed no cancer, versus 60% in the radiation-only group. Hormone therapy was well-tolerated by the majority of patients, and analyses are continuing to examine potential late side effects. Acute and late radiation toxicity was similar in both arms. Hormonal toxicity was mainly liver and was grade 3 or grade 4 in < 5% of patients. Hormonal cardiovascular toxicity was grade 1 or 2 in 13 patients (1%).

The authors added that recent advances in radiotherapy technology have led to the administration of higher radiation doses than those given to men in this study, so it remains uncertain whether hormone therapy would provide the same or greater benefit to current patients. To answer this question, RTOG recently opened a new trial (RTOG 0815) examining the role of hormone therapy combined with modern radiotherapy techniques for the same patient population – men with intermediate-risk, early-stage prostate cancer.