Relationship of age to histologic grade in prostate cancer.

We studied 4,968 cases of prostatic carcinoma to determine if there is a relationship between tumor grade and patient age at diagnosis. Cases were stratified into arbitrary age groups and classified as either better differentiated (Grades I and II) or worse differentiated (Grades III and IV). The 4,596 graded cases were distributed by stage as follows: Local 3,451 (75%), Regional 509 (11%), and Distant 636 (14%). When patients in all stages were considered together, the percentage of men with better differentiated tumors dropped from 77.8% of patients under 60 to 67.5% of patients 80 or older (P less than 0.00001). This trend for older patients to have more poorly differentiated tumors was also seen in patients with localized disease (P less than 0.0005). The fact that occult, biologically inactive prostate cancer is common in older men has led some to extrapolate that clinically apparent disease follows a more benign course in the elderly. Our findings suggest that, on the contrary, elderly men with clinically apparent disease have worse differentiated tumors than their younger counterparts.