Short- and Long-Term Outcomes of Robotic Surgery for Rectal Neuroendocrine Tumor

Background. The optimal radical surgical approach for rectal neuroendocrine tumor (NET) is unknown. Methods. This study evaluated the short- and long-term outcomes of 27 patients who underwent robotic radical surgery for rectal NET between 2011 and 2019. Results. The median distance from the lower border of the tumor to the anal verge was 5.0 cm. The median tumor size was 9.5 mm. Six patients (22%) had lymph node metastasis. The incidences of postoperative complications of grade II and grade III or more according to the Clavien–Dindo classification were 11% and 0%, respectively. All patients underwent sphincter-preserving surgery, and no patients required conversion to open surgery. The median follow-up time was 48.9 months, and both the 3-year overall survival and relapse-free survival rates were 100%. Conclusions. Short- and long-term outcomes of robotic surgery for rectal NET tumor were favorable. Robotic surgery may be a useful surgical approach for rectal NET.

Grade G2 Rectal Neuroendocrine Tumor Is Much More Invasive Compared With G1 Tumor

BackgroundTo compare clinicopathologic feature of rectal neuroendocrine tumor (NET) grade G1 with G2 NET.MethodsSix hundred-one cases of rectal G1 and G2 NETs diagnosed in our center were analyzed.ResultsOf 601 cases of rectal NET, 515 cases were with grade G1 and 86 cases were with grade G2. Median tumor size was 0.7 cm. Compared with G1 NET, G2 tumors were with significantly larger tumor size (0.8 vs 2.2 cm, p < 0.001), less percentages of patients with tumors confined to submucosa (92.6 vs 42.8%, p < 0.001), more frequent presence of microvascular invasion (MVI) (3.6 vs 16.9%, p < 0.001) or peri-neural invasion (PNI) (2.0 vs 24.1%, p < 0.001). Incidence of lymph node and distant metastasis was 5.2 and 2.1% in G1 NET compared with 44.2 and 31.4% in G2 tumor, respectively (p < 0.001). For tumors sized 1–2 cm and confined to submucosa, incidence of lymph node metastasis was 6.1% for G1 NET compared with 21.1% for G2 NET. Status of MVI/PNI was predictive of lymph node metastasis for G2 tumor rather than G1 NET in this subgroup.ConclusionsRectal G2 NET was much more invasive with significantly elevated prevalence of lymph node metastasis compared with G1 tumor.

Endoscopic resection is more effective than biopsy or EUS to detect residual rectal neuroendocrine tumor

Background and study aims Rectal neuroendocrine tumors (NETs) are often discovered incidentally and may be misidentified as adenomatous polyps. This can result in a partial resection at the index procedure, and lesions are often referred for staging or evaluation for residual disease at the resection site. The aim of this study was to identify the ideal method to confirm complete excision of small rectal NETs. Patients and methods Data from patients with a previously resected rectal NET referred for follow-up endoscopy or endoscopic ultrasound (EUS) were retrospectively reviewed. Univariate analysis was performed on categorical data using the Chi-squared test. Results Forty-nine patients with rectal NETs were identified by pathology specimens. Of those, 39 underwent follow-up endoscopy or EUS and were included. Baseline characteristics included gender (71 % F, 29 % M), age (57.2 ± 13.4 yrs) lesion size (7.3 ± 4.2 mm) and location. The prior resection site was identified in 37/39 patients who underwent tissue sampling. Residual NET was found histologically in 14/37 lesions. All residual disease was found during salvage endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) and 43 % had a normal-appearing scar. Every patient undergoing EUS had an unremarkable exam. Initial cold biopsy polypectomy (P = 0.006), visible lesions (P = 0.001) and EMR/ESD of the prior resection site (P = 0.01) correlated with residual NET. Conclusions Localized rectal NETs may be incompletely removed with standard polypectomy. If an advanced resection is not performed initially, repeat endoscopy with salvage EMR or ESD of the scar should be considered. For small rectal NETs, biopsy may miss residual disease when there is no visible lesion and EUS appears to have no benefit.