A secondary analysis of the SWOG 9346 data suggested that intermittent therapy was noninferior to continuous in patients with extensive disease but not minimal disease.
"The two studies targeted different populations," Dr. Crook said in an interview. "There are also some important differences in the way the results were handled in the statistical analysis. The results of the SWOG study are equivocal regarding survival."
"Our study has shown that men with only PSA evidence of recurrent prostate cancer and no evidence of metastatic disease can safely be treated with this intermittent program of androgen suppression to gain quality of life benefits without sacrificing length of life," she added.
"Our study did not address the optimal time to begin androgen ablation, or specifically how long intervention can be safely postponed."
The NCIC trial was supported by grants from the Canadian Cancer Society, the U.S. National Cancer Institute, and Hoeschst Marion Roussel Canada Research. Dr. Crook disclosed no relevant financial conflicts. Study coinvestigators disclosed financial relationships with numerous companies.
*This story was updated 9/6/2012.