Rapid cytological diagnosis of rectal cancer.

A simple, safe, rapid and accurate technique is described for cytological diagnosis of ulcerated or nodular rectal cancer done while performing digital rectal examination or sigmoidoscopy. In 21 cases, there were 17 true positives and no false positives for cancer. There were two true negatives and one false negative for rectal cancer. It is important to exclude prostatic cancer if, in the male, the lesion is anterior and situated at or near the level of the prostate gland, and this can be done using an immunoperoxidase technique which will identify cancer cells of prostatic origin.