Impact of time to testosterone rebound and comorbidity on the risk of cause-specific mortality in men with unfavorable-risk prostate cancer.

<bold>Background: </bold>Herein, the authors evaluated how the time to testosterone rebound (TTR) after radiotherapy (RT) and 6 months of androgen deprivation therapy (ADT) impacted the risk of prostate cancer-specific mortality (PCSM) and cardiovascular-specific mortality (CVM) among men with varying comorbidity extent.<bold>Methods: </bold>Between 1995 and 2001, a total of 206 men who were randomized to receive RT either alone or with 6 months of ADT for unfavorable-risk PC and who had a comorbidity score assigned using the Adult Comorbidity Evaluation 27 metric comprised the study cohort. Multivariable competing risk regression was used to evaluate the impact of and possible interaction between comorbidity and TTR on PCSM and CVM.<bold>Results: </bold>After a median follow-up of 18.19 years, 30 men (18.6%), 39 men (24.2%), and 92 men (57.1%), respectively, had died of PC, CV disease, or other causes. As TTR increased, PCSM significantly decreased in men with no or minimal (adjusted hazard ratio [AHR], 0.53, 95% confidence interval [95% CI], 0.34-0.84 [P =.007]) and moderate to severe (AHR, 0.37; 95% CI, 0.14-0.99 [P = .048]) comorbidity. However, increasing TTR significantly increased the risk of CVM among men with moderate to severe comorbidity (AHR, 1.87; 95% CI, 1.40-2.49 [P <.001]), but not those with no or minimal comorbidity (AHR, 0.86; 95% CI, 0.57-1.29 [P =.46]), leading to a significant interaction between TTR and comorbidity (P = .001).<bold>Conclusions: </bold>The results of the current study indicate that considering an intermittent course of ADT such that the TTR approaches 18 months, instead of continuous long-term administration of ADT, in men with moderate to severe comorbidity and high-risk PC may reduce the increased risk of CVM without increasing the risk of PCSM. Cancer 2018;124:1391-9. © 2018 American Cancer Society. [ABSTRACT FROM AUTHOR]