Pathological studies in rectal cancer

Abstract

In order to improve our selectivity in treating rectal cancer by local measures alone and to delineate patients most suitable for adjuvant preoperative (abdominoperineal resection) radiation therapy, we have evaluated rectal cancer size, configuration, and grade, and correlated this information with subsequent pathological findings. Data from 247 patients treated by abdominoperineal resection were analyzed. Only 15–20% of exophytic/moderately or well-differentiated tumors had gross transmural invasion, independent of size. Twelve percent of ulcerated/moderately or well-differentiated tumors >4 cm penetrated grossly through the wall, vs. 42% of those >4 cm. Sixty-seven percent of poorly-differentiated or colloid carcinomas >4 cm also had gross transmural penetration. These data suggest patients most likely to benefit from preoperative radiation therapy are those with poorly differentiated or colloid tumors, or with ulcerated lesions >4 cm in size of moderate or well-differentiated histology. All seven exophytic/well-differentiated carcinomas >4 cm, and 4/5 exophytic/moderately differentiated tumors >3 cm had penetration limited to the bowel wall only.