The mesenteric and antimesenteric location of colorectal cancer: the relationship with lymph nodes

Purpose of the study was to evaluate if the circumferential location of colorectal cancer may be identified as a possible prognostic factor. The hypothesis is that tumours located on the antimesenteric (AM) side could have a better prognosis than tumours located on the mesenteric (M) side.

All patients undergoing curative resection for colorectal cancer were enrolled in the study. The specimens were sent to the pathologist to define the exact location of the tumour, the histological type, grading, T, N status as well as lymphatic, vascular and neural invasion, peritumoural lymphoid reaction, desmoplasia and microsatellite instability. Statistical analyses were performed using the test for proportions (with continuity correction), the Pearson Chi-square test and generalised linear models; p<0.05 were considered statistically significant.

From August 2000 to August 2002, 255 patients were enrolled in the study. There was a significantly higher incidence of tumours located on the M (101) compared with the AM (37) site (p<0.0001). M located tumours were associated with higher numbers of metastatic lymph nodes (N1 and N2; p-value=0.014), whereas AM tumours were associated with involved lymph nodes in only 5/37 (13.5%) of tumours. There was no statistically significant relation between AM versus M location and T status: the Pearson Chi-Square test showed that the lymph node involvement and the location (M versus AM) are not statistically independent variables (p-value=0.014).

Our preliminary results show that when M or AM tumour identification is possible, tumour location can be regarded as a prognostic factor. Further longer studies on recurrence rate and survival are required to validate these findings and the clinical usefulness of this putative prognostic factor.