Population-based study of long-term survival in patients with clinically localised prostate cancer.

BACKGROUND: Choice of treatment in localised prostate cancer has been hampered by a lack of unbiased, representative data on outcome. Most existing data have come from small cohorts at specialised academic centres; precise overall and cancer-grade-specific data are not available, and the data are subject to differential staging bias. Randomised clinical trials have been undertaken, but the results will not be available for another decade. We have carried out a large population-based study to ascertain overall and prostate-cancer-specific survival in men treated by prostatectomy, radiotherapy, or conservative management. METHODS: Data for 59,876 cancer-registry patients aged 50-79 were analysed. We examined the effect of differential staging of prostate cancer by analysing the data both by intention to treat and by treatment received. Estimated survival was calculated by the Kaplan-Meier method. FINDINGS: By the intention-to-treat approach, 10-year prostate-cancer-specific survival for grade 1 cancer was 94% (95% CI 91-95) after prostatectomy, 90% (87-92) after radiotherapy, and 93% (91-94) after conservative management. The corresponding survival figures in grade 2 cancers were 87% (85-89), 76% (72-79), and 77% (74-80); those in grade 3 cancer were 67% (62-71), 53% (47-58), and 45% (40-51). Although the intention-to-treat and treatment-received analyses yielded similar results for radiotherapy and conservative management, the 10-year disease-specific survival after prostatectomy differed substantially (83% [81-84] by intention to treat vs 89% [87-91] by treatment received). INTERPRETATION: The overall and cancer-grade-specific survival found in this study differ substantially from those in previous studies. Previous studies that used a treatment-received approach have generally overestimated the benefits of radical prostatectomy. We found that grade 3 tumours are highly aggressive irrespective of stage.