Risk factors for recurrence after transanal endoscopic microsurgery for rectal malignant neoplasm

Background Indications and results of local excision of rectal lesions are currently under debate. Transanal endoscopic microsurgery (TEM), allowing a precise, full-thickness excision, could improve oncological results in early rectal tumors. Methods A prospective database was analyzed with the intent to identify risk factors for recurrence after TEM. Results Among 355 patients subjected to TEM, 107 had an adenocarcinoma: 48 pT1, 43 pT2, and 16 pT3. Comparing pre- and postoperative data, histological discrepancy was 20% and staging discrepancy was 34%. Mortality was nil, morbidity was 9%. Mean follow-up was 54.2 months (range = 12-164), follow-up rate was 100%. The 5-year disease-free survival rate was 85.9, 78.4, and 49.4% for pT1, pT2, and pT3, respectively (p = 0.006). Recurrence rate was 0% (0/26) in pT1sm1 cancers and 22.7% (5/22) in sm2-3 (p < 0.05). A submucosal infiltration represented a significant risk factor for recurrences: 0% sm1, 16.7% sm2, and 30% sm3. Recurrence in pT2 was 0% in patients who had neoadjuvant therapy and 26% in the others. At univariate analysis, diameter, sm stage, pT stage, tumor grading, margin infiltration, and lymphovascular invasion demonstrated statistical significance. Multivariate analysis indicated sm stage, pT stage, and tumor grading as independent predictors of recurrence. Conclusions TEM represents an effective curative treatment for pT1 sm1 rectal malignancies. pT1 sm2-3 patients should be considered high-risk cases if treated only by TEM. A consistent improvement in the preoperative assessment of the risk factors identified by the present study will be a crucial development for optimal treatment of early rectal cancers.