Clinicopathological Differences between Proximal and Distal pT3 Colon Cancer and the Clinical Significance of the Depth of Cancer Invasion beyond the Muscularis Propria.

Abstract Background/Aims: To investigate differences in clinicopathological features between proximal and distal pT3 colon cancers and to determine whether the depth of the cancer invasion beyond the muscularis propria (DBM) serves as an objective indicator of the depth of tumor invasion in proximal colon cancer and in distal colon cancer. Methodology: A total of 207 patients who underwent surgery for proximal and distal pT3 colon cancer between 1996 and 2001 were included in the analysis. Results: No differences were noted between proximal and distal cancers in lymph node metastasis, distant metastasis, lymphatic/venous invasion, histological type and curability of surgical resection, although proximal cancer patients were significantly older. High-grade malignancy appeared to be more commonly noted in the proximal colon cancer cases but there was no significant difference in prognosis between proximal and distal cancer patients. Conclusions: Regarding the correlation between DBM and prognosis, there was a significant decrease in the 5-year survival rate in patients with proximal lesions of DBM 3000μm or more, and patients with distal lesions of DBM 5000μm or more. DBM is thus an objective indicator of depth of tumor invasion for both proximal and distal lesions, a prognostic factor and a guide to determining whether postoperative adjuvant chemotherapy is indicated for pT3 colon cancer cases.