Posted April 16, 2005. Adding androgen-suppressing drugs to radiation therapy improves chances or long-term survival for men with high-risk prostate cancer
according to a study published April 2005 in the International Journal of Radiation Oncology Biology Physics, official journal of ASTRO (American Society for Therapeutic Radiology and Oncology).
From 1987 and 1992, before the advent of high-dose radiotherapy and in the relatively early days of hormonal blockade therapy, the study enrolled patients with "unfavorable" disease status -- men with palpable primary tumor extending beyond the prostate (clinical Stage T3) or those with evidence of cancer spread to regional lymph nodes.
Patients who had undergone prostatectomy were eligible if penetration through the prostatic capsule to the margin of resection and/or seminal vesicle involvement was documented by tissue biopsy. The patients were grouped according to tissue differentiation, nodal status, acid phosphatase status, and prior prostatectomy.
In all, 977 patients enrolled were separated into two groups: men who received radiation therapy only (classified for this study as the "observation" group or arm); and men who received added, "adjuvant" therapy aimed at boosting therapeutic effect. Those in the adjuvant arm received radiation therapy and Zoladex (goserelin acetate), a drug that suppresses the male hormone testosterone. The drug was to be started during the last week of RT and was to be continued indefinitely or until signs of progression.
The patients in the observation arm received Zoladex only if after radiation therapy alone they experienced a relapse.
As of July 2003, the median follow-up for all patients was 7.6 years and for surviving patients, 11 years.
At ten years, the overall survival rate was higher for men taking the Zoladex than those not taking it -- 49 percent to 39 percent, respectively.
The local failure rate at ten years for those taking Zoladex arm was 23 percent and higher, 38 percent, for the others; and the ten year rates for cancer spreading to other parts of the body were 24 percent for the patients on Zoladex versus 39 percent for the observation patients.
Finally, the prostate cancer-related death rate was 16 percent for men given Zoladex and 22 percent for those not.
Taking the Zoladex shots appeared to carry greater benefit for men with aggressive disease. The improvement in survival appeared preferentially in patients with a Gleason score of 7-10
"The results of the study firmly establish the role of adjuvant hormonal management in high-risk carcinoma of the prostate treated with definitive radiotherapy,” said Miljenko V. Pilepich, M.D., a radiation oncologist at the University of California, Los Angeles and lead author of the study.
Edited by J. Strax, April 16, 2005
Study summary (abstract) at pubmed.gov
Androgen Suppression Adjuvant to Definitive Radiotherapy in Prostate Carcinoma – Long-term Results of Phase III RTOG 85-31, Pilepich MV, et al. Int J Radiat Oncol Biol Phys. 2005 Apr 1;61(5):1285-90.
For more information on radiation therapy for prostate cancer, visit www.rtanswers.org
and for a free brochure go to: www.astro.org/patient/treatment_information/