Cause-specific actuarial survival analysis: a useful method for reporting survival data in men with clinically localized carcinoma of the prostate.

The primary objective of this retrospective 15-year survival analysis of 57 men with clinical stage B1 carcinoma of the prostate undergoing radical prostatectomy between 1951 and 1963 is to compute the cause-specific curve for these men and argue why it is a useful method to report survival data in men with clinically localized prostatic cancer. Historically, survival following radical prostatectomy and radiotherapy has been reported using all cause survival analysis. Cause-specific survival focuses on the impact of a disease process on survival, since men dying of causes unrelated to carcinoma of the prostate are considered lost to followup as of date of death of such unrelated causes. Cause-specific survival analysis reduces the impact of age, medical condition and other risk factors on survival rates. The cause-specific 15-year actuarial survival rate in our patients was 86 per cent. The 95 per cent confidence interval for this 15-year survival rate was 76.9 to 90.1 per cent. Based upon this series of patients with clinical stage B1 carcinoma of the prostate who undergo radical prostatectomy one may state that the chance of death of carcinoma of the prostate within 15 years of surgery averages 14 +/- 5 per cent. The cause-specific survival curve reached a plateau at 10 years, indicating that most men who survive 10 years are cured of the disease. With the Cox model regression analysis, mortality in this series was related positively to age at operation when the outcome variable was death of all causes (p equals 0.003) but it was unrelated to age when the outcome variable was prostate cancer mortality (p equals 0.85). Cause-specific survival rates are a more precise indicator of the impact of a therapeutic modality on survival and, therefore, they are useful to report survival data in men with localized carcinoma of the prostate and other disease when death from competing causes is an important consideration.