Background: No clear guidelines exist for managing localized prostate cancer because clinical studies have not yet established which treatment provides the best long-term outcome. We assessed the effect of treatment on prostate cancer-specific mortality considering the determinants of treatment and prognosis.
Methods: The population-based cohort included all 844 patients having a diagnosis of localized prostate cancer between January 1, 1989, and December 31, 1998, in Geneva, Switzerland. Treatments included prostatectomy (n = 158), radiotherapy (n = 205), watchful waiting (n = 378), hormone therapy (n = 72), and other types of therapy (n = 31). We compared survival curves using the log-rank test. With multivariate Cox proportional hazards analysis and propensity score methods, we evaluated the independent effect of treatments on prostate cancer-specific mortality.
Results: Treatment options only slightly influenced 5-year prostate cancer-specific mortality but had an important effect on long-term mortality. Ten-year specific survival was 83% (95% confidence interval [CI], 73%-93%), 75% (95% CI, 67%-83%), and 72% (95% CI, 66%-80%) for patients who underwent surgery, radiotherapy, and watchful waiting, respectively (P < .001). At 10 years, patients treated with radiotherapy or watchful waiting had a significantly increased risk of death from prostate cancer compared with patients who underwent prostatectomy (multiadjusted hazard ratio, 2.3 [95% CI, 1.2-4.3] and 2.0 [95% CI, 1.1-3.8], respectively). The increased mortality associated with radiotherapy and watchful waiting was primarily observed in patients younger than 70 years and in patients with poorly differentiated tumors (Gleason score > or = 7; reference, 1 [best]-10 [worst]). Patients who received hormone therapy alone already had an increased risk of prostate cancer-specific mortality at 5 years (hazard ratio, 3.5 [95% CI, 1.4-8.7]).
Conclusions: Our study results suggest that surgery offers the best chance of long-term prostate cancer-specific survival, in particular for younger patients and patients with poorly differentiated tumors. Until clinical trials provide conclusive evidence, physicians and patients should be informed of these results and their limitations.