Depth of mesorectal extension has prognostic significance in patients with T3 rectal cancer

Abstract

Introduction : More than half of all rectal cancers are T3 lesions, but they are classified as a single stage category. In the case of rectal cancer, some authors reported a prognostic influence of the mesorectal infiltration depth and have suggested that this parameter should be included in therapeutic decision-making. The aim of this study was to validate prognostic significance of mesorectal extension depth in T3 rectal cancer. Methods: We studied 291 patients with T3 rectal cancer who underwent a curative intent surgery between January 2003 and December 2009 at Seoul National University Hospital. This study is a retrospective analysis of oncologic outcomes of patients with T3 rectal cancer grouped by mesorectal extension depth (T3a: <1mm, T3b: 1~5mm, T3c: 5~15mm, T3d: >15mm). Oncologic outcomes in terms of disease-free survival were analyzed. Results: The 5-year disease free survival rate according to T3 subclassification was 86.5 % for T3a, 74.2 % for T3b, 58.3 % for T3c and 29.0 % for T3d, respectively. It was significantly higher in T3a, b tumors than that in T3c, d tumors (77.6% vs. 55.2%, p<0.001). On univariate and multivariate analysis, prognostic factors affecting recurrence were preoperative carcinoembryonic antigen (CEA) level ≥ ii 5ng/ml (hazard ratio =2.617, 95% CI 1.620-4.226), lymph node metastasis (hazard ratio =3.347, 95% CI 1.834-6.566) and mesorectal extension depth >5mm (hazard ratio =1.661, 95% CI 1.013-2.725). In subgroup analysis, independent prognostic factors were preoperative CEA level and mesorectal extension depth >5mm for 200 ypT3 rectal cancer patients and preoperative CEA level and lymph node metastasis for 91 pT3 rectal cancer patients. Conclusions: Depth of mesorectal extension >5mm is a significant prognostic factor in patients with T3 rectal cancer. Especially, depth of mesorectal extension may be more important than the nodal status in predicting the oncologic outcome for patients who had received preoperative chemoradiotherapy.