ABSTRACT
Objective:To compare the short- and long-term efficacy and safety of endoscopic submucosal dissection (ESD) and transanal endoscopic microsurgery (TEM) in the treatment of rectal neuroendocrine tumor (NET) with maximum diameter ≤20 mm.Methods:From January 1, 2014 to June 30, 2022, the clinical data of 111 patients with rectal NET with maximum diameter ≤20 mm treated by ESD or TEM at Peking University People′s Hospital were retrospectively analyzed. According to the treatment of ESD or TEM, 111 patients with rectal NET were divided into ESD group (76 cases) and TEM group (35 cases). The clinicopathological characteristics (age, distance from anal margin, depth of invasion, etc.) were compared between patients with tumor maximum diameter<10 mm and 10 to 20 mm, and between ESD group patients and TEM group patients. The clinical efficacy and prognosis were also compared between ESD group and TEM group. The follow-up time was 41 months (16 months, 76 months). The propensity score matching (PSM) method was used to balance the differences of clinical characteristics between ESD and TEM groups. Independent sample t test, Wilcoxon rank-sum and chi-square test were used for statistical analysis. The risk factors of lymph node or distant metastasis were analyzed by univariate and multivariate binary logistic regression. Results:The maximum tumor diameter of 111 patients with rectal NET was (6.6±0.3) mm (ranged from 2 to 20 mm). The maximum tumor diameter of 85 cases (76.6%) was <10 mm and that of 26 cases (23.4%) was between 10 mm and 20 mm. There were statistically significant differences in age, distance from the anal margin and incidence of submucosal infiltration between patients with tumor maximum diameter<10 mm and patients with tumor maximum diameter 10 to 20 mm ((49.8±11.6 ) years old vs. (56.8±13.8) years old; 5.0 cm (4.0 cm, 8.0 cm) vs. 8.0 cm (5.0 cm, 8.0 cm); 69.4%, 59/85 vs. 96.2%, 25/26; t=2.58, Z=-2.23, χ2=6.35, P=0.011, 0.026 and 0.012). The en block resection rate of rectal NET treated with ESD or TEM was 100.0%(111/111), the complete resection rate was 93.7% (104/111), and the postoperative bleeding rate was 2.7% (3/111). There were no postoperative perforation or other major complications. During the follow-up period, there was no local recurrence. The metachronous recurrent rate was 0.9% (1/111), 3.6% (4/111) patients had lymph node or distant metastasis, and there was no death. Compared with patients with tumor maximum diameter<10 mm, more patients with tumor maximum diameter of 10 to 20 mm selected TEM (57.7%, 15/26 vs. 23.5%, 20/85), and the difference was statistically significant ( χ2=10.76, P=0.001). Before PSM, a total of 7 patients in the ESD group had positive vertical margins, and during the follow-up of 21 months (15 months, 48 months), 2 patients had lymph node or distant metastasis and received surgery. The proportion of patients with tumor maximum diameter of 10 to 20 mm and submucosal invasion in TEM group were both higher than those in ESD group (42.9%, 15/35 vs. 14.5%, 11/76; 88.6%, 31/35 vs. 69.7%, 53/76), and the differences were statistically significant( χ2=10.76 and 3.65, P=0.001 and 0.032). After PSM, there were no statistically significant differences in the complete resection rate, postoperative bleeding rate, metachronous recurrence rate, lymph node or distant metastasis rate between ESD group and TEM group (89.3%, 25/28 vs.100.0%, 28/28; 3.6%, 1/28 vs. 0, 0/28; 3.6%, 1/28 vs. 0, 0/28; 0, 0/28 vs.3.6%, 1/28; all P>0.05). However, the operation time and hospital stay of the ESD group were both shorter than those of the TEM group (27.0 min (25.0 min, 30.0 min) vs. 39.0 min (32.0 min, 45.0 min); 5.0 d (4.0 d, 5.0 d) vs. 6.0 d (3.0 d, 9.0 d)), and the differences were statistically significant ( Z=-3.38 and -2.23, P=0.001 and 0.021). Conclusion:The efficacy of ESD and TEM in rectal NET with maximum diameter ≤ 20 mm is equal, however, ESD has the advantage of shorter procedure time and hospital stay.