Distal intramural spread of rectal carcinomas.

Forty-three consecutive specimens of resected rectal carcinomas, 16 abdominoperineal and 27 anterior resections, were examined for distal intramural spread. Thirty-four of the resections were considered curative and nine palliative. Eighteen carcinomas (42 percent) showed no distal spread, and 14 (33 percent) showed very limited distal spread (0-5 mm). In the remaining cases, 11 (25 percent) had distal spread of more than 5 mm and eight of more than 10 mm. The eight carcinomas with distal spread of greater than 10 mm were advanced Dukes' C tumors. Only three were considered curable. All potentially curable carcinomas would have been resected adequately with a distal margin of only 1.5 cm except one signet-ring carcinoma with extensive lymph node metastases located in the lower rectum.