Mahal BA, et al. - Researchers investigated if there exists a link between the timing of salvage androgen deprivation therapy (ADT) and prostate cancer (PC)-specific mortality (PCSM) among men with short vs long prostate-specific antigen doubling times (PSA-DTs). They found that, in men with a PSA-DT of ≥6 months, the risk of PCSM may be attenuated by early initiation of salvage ADT for post-radiation therapy (RT) PSA failure.

Methods

• From 206 men with localized unfavorable-risk PC randomly allocated to radiation therapy (RT) or RT plus 6 months of ADT between 1995 and 2001, researchers included in this study 54 men who received salvage ADT for PSA failure after a median follow-up of 18.72 years following randomization.
• They used the Fine-Gray competing risks regression model and determined if the timing of salvage ADT was related to an increased risk of PCSM, after adjusting for age, comorbidity, known PC prognostic factors, and previously identified interactions.

Results

• A median follow-up of 5.68 years (interquartile range, 3.05–9.56) was carried out after salvage ADT, during which the death of 49 of the 54 men (91%) was reported, PC accounted for 27 deaths (54% of deaths).
• Researchers found that as a continuous covariate (per month increase), increasing PSA-DT was related to a decreasing risk of PCSM (adjusted hazard ratio [HR], 0.33; 95% CI, 0.13–0.82; P=.02).
• They also observed an increased risk of PCSM (adjusted HR, 8.84; 95% CI, 1.99–39.27; P=.004) related to initiating salvage ADT later (PSA level >12 ng/mL, upper quartile) vs earlier among men with a long PSA-DT (≥6 months), whereas for those with a short PSA-DT (<6 months; adjusted HR, 1.16; 95% CI, 0.38–3.54; P=.79) this was not true.