Stratification of risk for lymph node metastasis and long-term oncologic outcomes in patients initially treated by endoscopic resection for rectal neuroendocrine tumors

Sung Sil Park; Byung Chang Kim; Dong-Eun Lee; Hee Jin Chang; Kyung Su Han; Bun Kim; Chang Won Hong; Dae Kyung Sohn; Dong Woon Lee; Kiho You; Sung Chan Park; Jae Hwan Oh

doi:10.1016/j.gie.2024.11.036

Stratification of risk for lymph node metastasis and long-term oncologic outcomes in patients initially treated by endoscopic resection for rectal neuroendocrine tumors

Gastrointest Endosc. 2024 Nov 26:S0016-5107(24)03746-5. doi: 10.1016/j.gie.2024.11.036. Online ahead of print.

Authors

Affiliations

¹ Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, South Korea.
² Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, South Korea. Electronic address: mdzara@ncc.re.kr.
³ Biostatistics Collaboration Team, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
⁴ Department of Pathology, Research Institute and Hospital, National Cancer Center, Goyang, Korea.

PMID: 39608591
DOI: 10.1016/j.gie.2024.11.036

Abstract

Background and aims: The treatment of rectal neuroendocrine tumors (NETs) is determined by the risk of lymph node (LN) metastasis. We aimed to stratify the risk of LN metastasis according to the number of risk factors and evaluate the long-term outcomes of patients initially treated endoscopically for rectal NETs.

Methods: We retrospectively analyzed 441 patients initially treated with endoscopy for rectal NETs; those who had at least one of the risk factors for LN metastasis were defined as high-risk patients. We stratified LN metastasis rates according to the number of risk factors. The 5-year overall survival (OS) and recurrence-free survival (RFS) were compared between the high- and low-risk groups.

Results: Pathologic size (odds ratio [OR], 1.208; 95% confidence interval [CI], 1.062-1.374; P=0.001), (+) resection margin invasion (OR, 2.897; 95% CI, 1.057-7.936; P=0.039), and angiolymphatic invasion (OR, 22.155; 95% CI, 7.563-64.904; P=0.001) were risk factors for LN metastasis. The rate of LN metastasis increased as the number of risk factors increased (P=0.001). The 5-year RFS rates were 98.7% and 99% in the high- and low-risk groups, with no significant difference (P=0.966). The 5-year OS rates were 100% and 99.5% in the high- and low-risk groups, with no significant difference (P=0.571).

Conclusions: The risk of LN metastasis increased significantly when the number of risk factors increased in patients with rectal NETs. Patients who initially underwent endoscopic resection for rectal NETs showed a favorable long-term oncologic outcome if salvage treatments were performed, depending on the stratification of their risk factors.

Keywords: Lymphatic metastasis; Neuroendocrine tumors; Rectal Neoplasms; Risk factors; Survival.