Predicting Life Expectancy in Men With Clinically Localized Prostate Cancer

Abstract

The choice of appropriate management for localized prostate cancer depends in part on the estimated life expectancy of a man. Little is known about the accuracy of existing rules for deriving these estimates. We developed a new prediction rule and examined the accuracy of 2 others in our data set. A retrospective cohort was assembled, consisting of 506 men who were diagnosed or received initial treatment at a community based, tertiary care health center between 1987 and 1989 for clinically localized prostate cancer (stages A, B, I, II or T1–2N0M0) and had at least 13 years of followup. Most patients did not have prostate specific antigen levels available. Proportional hazards regression was used to create a nomogram for deriving survival estimates. Discrimination of the new and external prediction rules was assessed by the c-statistic. Calibration curves compared predicted to actual survival at 10 years. Estimates for survival at 5, 10 and 15 years, and for median life expectancy were determined. Discrimination was modest with a c-statistic of 0.73. The rules of Albertsen and Tewari et al had comparable discrimination in our data with a c-statistic of 0.71 and 0.70, respectively. Predicted life expectancy according to our rule and that of Tewari approximated actual survival experience. Predictions according to the Albertsen study underestimated actual survival in our group but in consistent fashion. Overall life expectancy can be predicted with a moderate degree of accuracy, sufficient for informing patient-clinician discussions but inadequate as the only determinant of the optimal management approach.