Histologic grading study of prostate adenocarcinoma: the development of a new system and comparison with other methods--a preliminary study.

A new grading system for adenocarcinoma of the prostate (MDAH System) and its simplified version, both based on the percentage of tumor that is differentiated (gland-forming) or undifferentiated (non-gland-forming), were compared with the grading systems of Mostofi and Gleason. In a study group of 182 patients with Stage C adenocarcinoma of the prostate, the MDAH system identified 84 patients (46%) as Grade 1, 75 (41%) as Grade 2--3, and 23 (13%) as Grade 4. Kaplan-Meier survival curves predicted a 91% five-year survival for Grade 1 patients, a 60% 5-year survival for Grade 2--3 patients, and a 15% five-year survival for Grade 4 patients. Wilcoxon (Gehan modification) tests showed that the survival was significantly different among Grades 1, 2--3, and 4. The MDAH System is an improvement over other grading systems in that it is a simple, low-power microscopic method that depends only on the percentage of gland formation in the tumor and further reflects the biologic behavior of the tumor as measured by the patient's survival.