Histologic grading of primary prostatic cancer: a new approach to an old problem.

A simple and objective system for grading prostatic carcinoma was evaluated in a retrospective analysis of 169 cases followed during a 16-year period. The system identified and separated 4 grades of increasing malignancy based on the combined evaluation of gland differentiation and nuclear anaplasia as separate but complementary factors. The system demonstrates significant correlation with mortality rates for each grade group. Retrospective evaluation of the extent of the disease at the time of initial diagnosis also indicates correlation between prostatic grades and clinical stages.