Brachytherapy for Intermediate-Risk Prostate Cancer, Androgen Deprivation, and the Risk of Death

To determine whether the use of 6 months' adjuvant androgen deprivation therapy (ADT) combined with brachytherapy for intermediate-risk (IR) and low-risk (LR) prostate cancer is associated with an increased risk of cardiovascular death.

This is a retrospective analysis of prospectively collected data from men treated in the British Columbia Cancer Agency brachytherapy program from 1998 to 2012. Men were categorized by risk group and ADT use. Cardiac and other comorbidities were recorded and compared between groups. Biochemical control (Phoenix definition, nadir + 2 ng/mL) was ascertained. Overall, prostate, cardiac, and other-cause mortality were analyzed by the Kaplan-Meier method and Fine and Gray competing-risk analysis.

The study included 3155 men (1142 with LR cancer and 2013 with IR cancer) who have been followed up for a median of 7.9 years. ADT was received by 47% of IR patients and 37% of LR patients for a median of 6 months. Men with IR cancer were older and had more cardiac and other comorbidities than LR cases (P<.01). Biochemical control improved from 86% to 89% at 10 years with the use of ADT (P=.006). Overall survival was inferior in patients receiving ADT (84% vs 86% at 10 years, P=.0274), and on competing-risk analysis, cardiovascular mortality in patients receiving ADT was higher in IR cases, 5.2% versus 3.6% at 10 years (P=.0493), but not in LR cases. Multivariate analysis confirmed increased cardiac mortality in IR patients receiving ADT (hazard ratio, 1.95 [95% confidence interval, 1.15-3.34]; P=.014).

ADT adds little meaningful benefit in terms of biochemical control for IR men treated with low-dose-rate brachytherapy but likely decreases overall survival because of increased cardiac mortality. IR patients were older and had more cardiac risk factors than LR prostate cases; this may be because of a screening effect, case selection, or common etiologic cause.