Predictors of clinical metastases and survival among nonmetastatic prostate cancer (PC) patients (pts) treated with androgen-deprivation therapy (ADT) in Sweden.

Abstract

e16066 Background: ADT is the standard of care in Sweden for PC pts with signs of recurrence after primary therapy (tx). Studies of predictors of metastasis (mets) and survival have largely focused on pt characteristics at cancer diagnosis. Time-varying factors, such as prostate-specific antigen (PSA) levels, may have greater impact on a pt’s risk of disease progression. This study examines predictors of mets and survival among men with PC treated with ADT. Methods: Using electronic medical records from Swedish urology clinics linked to national registries (Cancer Registry, National Pt Registry, Cause of Death Registry), we identified men with PC and no evidence of mets treated with ≥6 months (mos) ADT (gonadotropin-releasing hormone agonists/antagonists or bilateral orchiectomy) between 2000-2010 with ≥2 PSA values. Men were followed from ADT index date to mets, death, or end of follow-up (12/31/2010). Multivariate competing risks regression analysis was used to estimate hazard ratios (HR) and 95% CIs; predictors and covariates of interest included PC diagnosis year (yr), age, comorbidities, anti-androgen tx, region, and time-varying characteristics (PSA absolute value, PSA doubling time [DT]). Results: Cohort was 446 men with mean follow-up of 3.3 yrs. Most mets were to the bone (7-yr cumulative incidence 25% for bone, 30% for any mets). Median survival was 6 yrs (5.9 mos after bone mets, 6.1 mos after any mets). Higher PSA and shorter PSA DT were strong predictors of all outcomes. In particular, PSA DT ≤ 6 mos was associated with increased risk of bone mets (13.9 [8.0 – 24.1]), any mets (7.9 [4.9 – 12.8]), mortality (5.7 [3.9 – 8.5]), and bone mets-free survival (6.9 [4.7–10.1]) when compared to PSA DT > 6 mos. HRs were adjusted for age, Charlson comorbidity index, anti-androgen tx, and region. Conclusions: PC pts treated with ADT are at significant risk of bone mets, any mets, and death. This study based on real-world data demonstrates the importance of PSA measured after ADT initiation in defining high risk of these outcomes, particularly PSA DT ≤6 mos. PC pts may benefit from new tx to prevent disease progression since survival is short after bone or other mets.