Temporal trend in risk of prostate cancer death in men with favourable-risk prostate cancer.

Background and objectives: Changes in work-up and histopathological assessment have caused stage and grade migration in men with prostate cancer (PCa). The aim of this study was to assess temporal trends in risk of PCa death for men with favourable-risk PCa managed with primary radical prostatectomy or observation.

Methods and material: Men aged 75 or younger with Charlson Comorbidity index 0-1 diagnosed with favourable-risk PCa (T1-T2, prostate specific antigen [PSA] <20 ng/mL and Gleason score 6 or 7[3+4]) in the period 2000-2016 who were treated with primary radical prostatectomy or managed with observation in PCBaSe 4.0. Treatment groups were compared following propensity score matching, and risk of PCa death was estimated by use of Cox regression analyses.

Results: A total of 9,666 men were selected for each treatment strategy. The 7-year cumulative incidence of PCa death decreased in all risk and treatment groups. For example, the incidence in men diagnosed with low-risk PCa and managed with observation was 1.2% in 2000-2005, which decreased to 0.4% in 2011-2016. Corresponding incidences for men with intermediate-risk PCa managed with observation were 2.0% and 0.7%. The relative risk of PCa death was lower in men with low-risk PCa managed with radical prostatectomy compared to observation: in 2000-2005 hazard ratio (HR) 0.20 (95% confidence interval [CI] 0.10-0.38) and in 2011-2016 HR 0.35 (95% CI 0.05-2.26). Corresponding risks for men with intermediate-risk PCa were HR 0.28 (95% CI 0.16-0.47) and HR 0.21 (95% CI 0.04-1.18). The absolute risk reduction of radical prostatectomy compared to observation for men with low-risk PCa was 1% in 2000-2005 and 0.4% in 2011-2016, and for men with intermediate-risk PCa 1.1% in 2000-2005 and 0.7% in 2011-2016.

Conclusion: Men diagnosed in 2011-2016 with low-risk and favourable intermediate-risk PCa have a similar relative benefit but smaller absolute benefit of curative treatment compared to men diagnosed in 2000-2005.