Transanal endoscopic microsurgery had comparable 5-year relative survival to total mesorectal excision in T1 rectal cancer but inferior 5-year relative survival in T2 rectal cancer. Transanal endoscopic microsurgery was associated with higher local recurrence rates for both T1 and T2 tumors.

In this series, age increased the risk of in-hospital morbidity and 100-day mortality. Cr-POSSUM, SRS and ACPGBI overestimated 30-day mortality but predicted 100-day mortality with a high degree of accuracy. POSSUM correctly predicted in-hospital morbidity.

Purpose While local excision by transanal endoscopic microsurgery (TEM) or transanal minimally invasive surgery (TAMIS) is an option for low-risk early rectal cancers, inaccuracies in preoperative staging may be revealed only upon histopathological evaluation of the resected specimen, demanding completion surgery (CS) by formal resection. The aim of this study was to evaluate the results of CS in a national cohort. Method This was a retrospective analysis of national registry data, identifying and comparing all Norwegian patients who, without prior radiochemotherapy, underwent local excision by TEM or TAMIS and subsequent CS, or a primary total mesorectal excision (pTME), for early rectal cancer during 2000–2017. Primary endpoints were 5-year overall and disease-free survival, 5-year local and distant recurrence, and the rate of R0 resection at completion surgery. The secondary endpoint was the rate of permanent stoma. Results Forty-nine patients received CS, and 1098 underwent pTME. There was no difference in overall survival (OR 0.73, 95% CI 0.27–2.01), disease-free survival (OR 0.72, 95% CI 0.32–1.63), local recurrence (OR 1.08, 95% CI 0.14–8.27) or distant recurrence (OR 0.67, 95% CI 0.21–2.18). In the CS group, 53% had a permanent stoma vs. 32% in the pTME group (P = 0.002); however, the difference was not significant when adjusted for age, sex, and tumor level (OR 2.17, 0.95–5.02). Conclusions Oncological results were similar in the two groups. However, there may be an increased risk for a permanent stoma in the CS group.

Age caused treatment to be modified; there was less surgery for patients over 85 years, less radiochemotherapy over 80 years, and less major radical surgery over 75 years. This strategy resulted in more local recurrences among the elderly, although no certain effect on relative survival was observed.