PurposeWhether treating prostate cancer survivors with a depressive disorder with antidepressants can affect their cancer outcomes is unknown. We evaluated the association between antidepressant use and prostate cancer recurrence, in survivors with comorbid depressive disorders.MethodsWe conducted a longitudinal cohort study of 10,017 men with prostate cancer (stages I-II) diagnosed who also had a comorbid depressive disorder followed a maximum of 22 years, and examined rates of biochemical recurrence by antidepressant medication use. We conducted multivariable Cox models based on time-dependent antidepressant drug use status, and examined the risk of biochemical recurrence by cumulative duration of antidepressant use.ResultsOf these 10,017 survivors, 1842 (18%) experienced biochemical recurrence over 69,500 person-years of follow-up. The prostate cancer biochemical recurrence rate was greater with antidepressant non-use (31.3/1000 person-years) compared to antidepressant use (23.5/1000 person-years). In Cox proportional hazards multivariable adjusted models, non-use of antidepressants was associated with a 34% increased risk of biochemical recurrence compared to antidepressant use (HR = 1.34, 95% CI: 1.24-1.44). Longer use of antidepressants was associated with a lower biochemical recurrence risk (P trend test < 0.001).ConclusionUntreated depressive disorders in prostate cancer patients may be associated with an increased risk of biochemical recurrence.