Transanal endoscopic microsurgery was associated with higher recurrence rate in both low- and high-risk T1 rectal...

Optimal treatment of T1 rectal cancer (RC) remains to be determined. The aim of this study was to compare recurrence rates after transanal endoscopic microsurgery (TEM) and surgical resection according to risk groups. MATERIAL AND METHODS: This registry-based nationwide cohort study collected data on patients diagnosed with pT1 RC undergoing TEM or surgical resection (January 2009-December 2022) from the Swedish Colorectal Cancer Registry. Differences in recurrence rates were compared using Chi-square and log-rank tests, and were further analyzed using Cox- and logistic regression models.

A total of 228 and 631 patients undergoing TEM and surgical resection, respectively, with a median follow-up time of 59.7 months were identified. Overall recurrence rates were 11% in patients undergoing TEM and 5% following surgical resection, which was reflected in a lower five-year disease-free interval after TEM compared to surgery (88 vs. 95%, p = 0.002), with a HR of 2.83 (95% CI 1.56-5.13) after adjusting for sex, age at diagnosis, ASA class, LVI, PNI, mucinous subtype, submucosal invasion, and resection margin. The overall recurrence was higher following TEM compared to surgical resection in both low-risk (OR 5.31, 95% CI 1.10-25.56) and high-risk groups (OR 2.39, 95% CI 1.22-4.66). This corresponded to higher local recurrence rates after TEM compared to surgical resection in patients with high-risk tumors (8 vs. 1%, OR 6.96, 95% CI 2.40-20.17) and low-risk tumors (8 vs. 0%, p = 0.016, logistic regression not applicable), whereas no difference in distant recurrence rates was observed between the groups.

This nationwide registry-based cohort study showed that the local recurrence rate after TEM was significantly higher than after surgical resection, even in low-risk pT1 RC. These findings highlight the need for increased awareness of the risk of recurrence after TEM in early RC.