A Study on Distal Intramural Tumor Spread in Rectal Cancer

Kazuo Hase, Hidetaka Mochizuki, Sachio Yokoyama, Kazuyoshi Yoshimura, Tetsuhisa Yamamoto, Eishu Nakamura, Hiroyuki Kurihara, Tsukasa Yoshizumi, Hideki Ueno, Kazutsugu Iwamoto, Shoetsu Tamakuma

First Department of Surgery, National Defense Medical College

Two hundred and ninety-seven rectal cancer specimens were examined retrospectively for microscopic distal intramural tumor spread (DIS). DIS was revealed in 67 cases [DIS (+): 23%]. Among those, 58 showed DIS of 2 cm or less, whereas 9 showed DIS of longer than 2 cm. The maximum DIS was 3.7 cm. DIS (+) cases showed a worse surgical outcome than those without DIS [DIS (-)]. The curative resection rate was only 34% in DIS (+) cases, whereas it was 77% in DIS (-) cases. The tumor recurrence rate was higher and the cumulative 5-year survival rate was lower in DIS (+) cases than DIS (-) cases (57% vs 25%, p<0.005; 36% vs 74%, p<0.001, respectively). On pathological study of these rectal tumors, four characteristics were identified as risk factors for DIS of longer than 2 cm: l) ulceration and an ill-defined border; 2) poorly differentiated type or signet-ring cell type; 3) a diameter of longer than 6 cm; 4) annular or semiannular shape. Patients with one or no risk factors had no DIS of longer than2 cm, whereas the rate of DIS of longer than 2 cm in the patients with 2 or more risk factors was 11% (p,<0.005). It is concluded that a distal surgical margin of 4 cm should be left for rectal cancer with 2 or more risk factors, while 2 cm might be enough for cancer with one or no risk factors.

Key words
distal intramural spread of rectal cancer, postoperative prognostic factor of rectal cancer, distal surgical margin of rectum

Reprint requests
Kazuo Hase First Department of Surgery, National Defense Medical College
3-2 Namiki, Tokorozawa, 359 JAPAN

Accepted
September 9, 1992

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