Unexpected rectal cancer after TEM: outcome of completion surgery compared with primary TME.

Background: Transanal endoscopic microsurgery (TEM) has gained wide-spread acceptance as a safe and useful technique for the resection of rectal adenomas and selected T1 malignant lesions. If the lesion appears >T1 rectal cancer after resection with TEM, a completion TME resection is recommended. The aim of this study was to investigate the results of TME surgery after TEM for rectal cancer.

Methods: In four tertiary referral hospitals for TEM, all patients with completion TME surgery after initial TEM were selected. All eligible patients who were treated with 5 × 5 Gy radiotherapy followed by TME surgery from the Dutch TME trial were selected as reference group. A multivariate logistic regression model was used to calculate odds ratio's (OR) for colostomies and for colo- and ileostomies combined. Local recurrence and survival rates were compared in hazard ratio's (HR) using the multivariate Cox proportional hazard model.

Results: Fifty-nine patients were included in the TEM-COMPLETION group and 881 patients from the TME trial. In the TEM-COMPLETION group, 50.8% of the patients had a colostomy compared to 45.9% in the TME trial, OR 2.51 (p < 0.006). There is no significant difference when ileo- and colostomies are analyzed together. In the TEM-COMPLETION group, 10.2% developed a local recurrence compared to 5.2% in the TME trial, HR 6.8 (p < 0.0001).

Conclusions: Completion TME surgery after TEM for unexpected rectal adenocarcinoma results in more colostomies and higher local recurrence rates compared to one stage TME surgery preceded with preoperative 5 × 5 Gy radiotherapy. Pre-operative investigations must be optimized to distinguish malignant and benign lesions and prevent avoidable local recurrence and colostomies.