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

BACKGROUND AND AIMS

The treatment of rectal neuroendocrine tumors (NETs) is determined by the risk of lymph node (LN) metastasis. The aim of this study was 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 1 of the risk factors for LN metastasis were defined as high-risk patients. LN metastasis rates were stratified according to the number of risk factors. Five-year overall survival and recurrence-free survival 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 = .001), resection margin invasion (+) (OR, 2.897; 95% CI, 1.057-7.936; P = .039), and angiolymphatic invasion (OR, 22.155; 95% CI, 7.563-64.904; P = .001) were risk factors for LN metastasis. The rate of LN metastasis increased as the number of risk factors increased (P = .001). The 5-year recurrence-free survival rates were 98.7% and 99% in the high- and low-risk groups, respectively, with no significant difference (P = .966). The 5-year overall survival rates were 100% and 99.5% in the high- and low-risk groups, with no significant difference (P = .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 exhibited a favorable long-term oncologic outcome if salvage treatments were performed, depending on the stratification of their risk factors.