Diagnosis of adenocarcinoma in transurethral resectates of the prostate gland.

The often-posed question of how much prostate tissue should be examined microscopically to detect carcinoma in transurethral prostatectomy specimens was approached by prospective study and probability analysis. Transurethrally resected prostate specimens were weighed, totally embedded, and examined histologically in 151 consecutive cases. Resected fragments and fragments involved by carcinoma were enumerated for each case. Adenocarcinoma was diagnosed in 39 (25.8%) of the cases. Specimens containing carcinoma had a mean of 111 total fragments, with a median of 3 and mean of 7 positive fragments. In two clinically unsuspected cases of poorly differentiated adenocarcinoma, the number of fragments involved by carcinoma was small (2 of 164 and 4 of 190 fragments). Assuming that study of a single microscopic section of a fragment determines whether carcinoma is present, probability formulations are presented expressing the likelihood that at least one fragment containing cancer is found in randomly selected fragments from a specimen. To achieve a 95% probability of detecting carcinoma in TUR specimens, a minimum of 95% of the fragments must be examined if one fragment contains a carcinoma, 63.1% of the fragments if three contain carcinoma and 25.8% of the fragments if 10 contain carcinoma. Literature review indicates many authors recommend examining fewer fragments of transurethrally resected prostate tissue than this study indicates are required to diagnose carcinoma.