ORLANDO – Bicalutamide significantly improved overall survival of men with locally advanced, nonmetastatic prostate cancer, but offered no additional benefit for men with localized disease, investigators reported.
Dr. Frederic Birkabaek Thomsen
Long-term follow-up results from the randomized controlled Scandinavian Prostate Cancer Group 6 study show that after a median follow-up of 14.6 years, men with locally advanced disease who received 150 mg bicalutamide (Casodex) daily in addition to standard care had significantly better overall survival (OS) than did men with locally advanced disease who received a placebo (hazard ratio 0.77, P =. 01), reported Dr. Frederic Birkabaek Thomsen of Rigshopitalet at the University of Copenhagen, Denmark.
In contrast, men with localized disease had no benefit from bicalutamide (HR 1.19, P = .056).
“There was an even distribution between prostate cancer–specific mortality in both patients with localized and locally advanced disease. However, in patients with localized disease, there was an increase in other-cause mortality of patients randomized to bicalutamide. In contrast, in locally advanced disease, there was a slight increase in other-cause mortality in patients randomized to placebo, Dr. Thomsen said at the Genitourinary Cancers Symposium sponsored by the American Society of Clinical Oncology.
The current analysis builds on earlier findings from the study. In 2006, the investigators reported that after a median 7.1 years of follow-up, bicalutamide in patients with locally advanced disease significantly improved both progression-free survival (HR 0.47; P < .001) and overall survival (HR 0.65, P = .001).
The study enrolled 1,218 patients; 607 were assigned to bicalutamide, 611 to placebo. The groups were well matched by median age (70 years in each group), median prostate-specific antigen (PSA; 13.8 and 12.6 ng/mL, respectively), and tumor grade and disease stage.
In each treatment arm, at least 89% of patients were managed with watchful waiting, about 12% had radical prostatectomy, and 4%-6% had radiation with external beam or brachytherapy.
In the cohort as a whole, there was no difference between treatment arms in overall survival at 14.6 years’ median follow-up. But when the results were stratified by clinical tumor stage, there was, as noted above, a significant survival advantage from bicalutamide among patients with locally advanced disease.
An analysis stratifying survival by tumor stage and baseline PSA suggested that bicalutamide was most effective in men with locally advanced cancer and more extensive disease at baseline, with a nonsignificant hazard ratio of 0.87 for those with a baseline PSA around 10 ng/mL, compared with 0.76 (P = .015) for men with a baseline PSA hovering around 30 ng/mL.
Dr. Thomsen noted that although other studies from the United States and Europe have failed to show a benefit of bicalutamide in patients with locally advanced prostate cancer, patients in other trials received bicalutamide as an adjuvant to radical prostatectomy or radiation, whereas the majority of patients in the Scandinavian trial were managed with observation alone. Patients in the trial were also younger and tended to have more advanced disease than patients in other trials, which may explain the bicalutamide benefit they saw, he added.
Dr. Thomsen presented the findings in an oral abstract session and scientific poster session.