Pathological Study of Distal spread by whole Mount Sections of Mesorectum to Determine the Optimal Resection Margin in Patient with Rectal Cancer

Yoshifumi Shimada, Yasumasa Takii, Chizuko Kanbayashi, Tatsuya Nomura, Satoru Nakagawa, Hiroshi Yabusaki, Nobuaki Sato, Yoshiaki Tsuchiya, Atsushi Nashimoto and Otsuo Tanaka

Division of Surgery, Niigata Cancer Center Hospital

Background: General Rules for Clinical and Pathological Studies on Cancer of the Colon, Rectum, and Anus (Japanese-language edition 7) state that a 3 cm distal resection margin is needed in patients with rectal cancer in whom the distal edge is located above the peritoneal reflection (RS, Ra) and 2 cm needed when the distal edge is below it (Rb). To determine the optimal margin, we analyzed clinicopathologic features in the intestinal and mesorectal distal spread of rectal cancer using whole mounted sections of the mesorectum. Methods: We studied intestinal and mesorectal distal spread using whole mounted sections from 213 specimens of rectosigmoid and rectal cancer, analyzing the risk factors in intestinal and mesorectal distal spread. We defined the long distal spread as 30 mm or more in patients with RS/Ra cancer and 20 mm or more in those with Rb/P cancer, clarifying their clinicopathological features. Results: We found that 31 patients (15%) had distal spread, 20 intestinal distal spread alone, five mesorectal distal spread alone, and six both intestinal and mesorectal distal spread. Multivariate analysis indicated risk factors for intestinal distal spread to be histological grade (tub2, por) and distant metastasis and for mesorectal distal spread to be distant metastasis. All of the three (1.4%) having long distal spread, four or more lymph node involved (pN2) and two had distant metastasis. Conclusions: Distant metastasis is a risk factor in intestinal and mesorectal distal spread. Distal resection margins defined by the general rules are therefore appropriate for most patients with rectosigmoid and rectal cancer, but it should be considered that long distal spread may be observed in patients with pN2 and distant metastasis.

Key words
rectal cancer, distal spread, intestinal distal spread, mesorectal distal spread, whole mount section

Reprint requests
Yoshifumi Shimada Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences
1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510 JAPAN

Accepted
April 22, 2009

To read the PDF file you will need Abobe Reader installed on your computer.