March 25, 2009 – Men who continued on hormonal therapy for at least five years after their treatment for locally advanced prostate cancer lived longer than men who discontinued their therapy sooner, reports the Radiation Therapy Oncology Group (RTOG).
RTOG investigators detail their findings in a paper published online ahead of print by the Journal of Clinical Oncology. RTOG is a National Cancer Institute-funded national clinical trials group and is administered by the American College of Radiology.
RTOG investigators and other researchers have previously shown that adding androgen deprivation therapy (ADT) to pelvic radiotherapy improves survival for men with locally advanced prostate cancer, however the optimal duration of the hormonal therapy has not yet been established.
In a secondary analysis of a large randomized trial (RTOG 8531) that compared radiotherapy alone versus radiotherapy plus adjuvant ADT until disease progression, the authors identified a cohort of 189 patients who discontinued their assigned ADT despite no evidence of disease recurrence. The analysis found that men who continued ADT for five or more years had five- and 11-year overall survival rates of 100 and 63.9 percent as compared to 66.7 and 33.1 percent for those with more than one year and less than five years of ADT and 71.9 and 41.7 percent for men with less than one year of ADT. The authors also reported improved disease-free survival and decreases in local failure and distant metastasis with ADT greater than five years. These results held even after adjusting for known prognostic variables such as age, prostate surgery, nodal status, stage, and central review of Gleason scores.
“Although our analysis gives strong support to the hypothesis that long-term hormonal therapy leads to better outcome than the standard two to three year regimen, it is clear that a well-designed randomized trial is needed to definitively answer this question,” said Louis Souhami, M.D., the lead author of the paper and a professor in the Department of Radiation Oncology at McGill University in Montreal, Quebec, Canada.
Source: Souhami L, Bae K, Pilepich M, Sandler H: Impact of the Duration of Adjuvant Hormonal Therapy in Patients With Locally Advanced Prostate Cancer Treated With Radiotherapy: A Secondary Analysis of RTOG 85-31, Journal of Clinical Oncology. (http://jco.ascopubs.org/cgi/content/abstract/JCO.2008.17.4052v1).
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