Intersphincteric resection for very low rectal adenocarcinoma: Univariate and multivariate analyses of risk factors for recurrence

Background: The aim of this study was to analyze the risk factors for local and distant recurrence after intersphincteric resection (ISR) for very low rectal adenocarcinoma. Methods: One hundred twenty consecutive patients with T1-T3 rectal cancers located 1-5 (median 3) cm from the anal verge underwent ISR. Univariate and multivariate analyses of prospectively recorded clinicopathologic parameters were performed. Results: Fifty patients had disease categorized as stage I, 21 as stage II, 46 as stage III, and 3 as stage IV on the basis of International Union Against Cancer tumor, node, metastasis staging system. Median follow-up time was 3.5 years. The 3-year rates of local and distant recurrence were 6% and 13%, respectively. Univariate analysis of the risk factors for local recurrence revealed pathologic T, pathologic stage, focal dedifferentiation, microscopic resection margins, and preoperative serum CA 19-9 level to be statistically significant. Multivariate analysis showed resection margin, focal dedifferentiation, and serum CA 19-9 level to be independently significant. Univariate analysis of the risk factors for distant recurrence indicated tumor location, combined resection, tumor annularity, pathologic N, lateral pelvic lymph node metastasis, pathologic stage, histologic grade, lymphovascular invasion, perineural invasion, and adjuvant chemotherapy to be significant. Multivariate analysis identified pathologic N, histologic grade, and tumor location to be independently significant. Conclusion: Profiles of risk factors for local and distant recurrences after ISR are different. With local recurrence, the resection margin, focal dedifferentiation, and serum CA 19-9 level are important. For distant recurrence, the lymph node status, histologic grade, and tumor location need to be taken into account.