Retroperitoneal margin involvement by adenocarcinoma of the caecum and ascending colon: what does it mean?

Objective Circumferential margin involvement (CRM) is a powerful predictor of local recurrence, distant metastasis and patient survival in rectal cancer. In this study, we aimed to determine the frequency of retroperitoneal margin involvement in right colon cancer and describe its relationship to tumour stage and outcome of surgical treatment. Method Two hundred and twenty-eight consecutive resections for adenocarcinoma of the ascending colon and caecum were identified between 1998 and 2006. Tumour involvement of the posterior retroperitoneal surgical resection margin (RSRM) was recorded and correlated with tumour stage, grade and clinical outcome. RSRM positive patients were compared with CRM positive rectal tumours resected in the same surgical unit. Results Nineteen of 228 right hemicolectomies (8.4%) showed tumour involvement of the RSRM (defined as <= 1 mm). Approximately half of the RSRM positive patients underwent palliative resections because of synchronous distant metastases. Out of nine 'potentially curative' resections where the RSRM was involved, five patients subsequently developed metastatic recurrence and two isolated local recurrence. RSRM positivity was associated with advanced tumour stage and more extensive extramural spread than CRM positive rectal cancers. Conclusion Retroperitoneal surgical resection margin involvement by caecal and ascending colon carcinoma is a marker of advanced tumour stage and associated with a high incidence of synchronous and metachronous distant metastasis. More aggressive surgery to obtain a clear margin or postoperative radiotherapy to the tumour bed is likely to benefit only a minority of patients.