Surgical and Oncologic Outcomes of Primary Tumor Resection in Patients with Small Intestinal Neuroendocrine Tumors: Results from a Single-Center Series Over a 15-Year Period.

Background: The role of prophylactic primary tumor resection (PTR) in patients with small intestinal neuroendocrine tumors (SI-NETs) and unresectable liver metastases is a matter of debate.

Objective: We aimed to evaluate outcomes in patients with SI-NETs who underwent PTR, according to the presence of metastasis and symptoms from primary.

Material And Methods: Data from patients who underwent PTR for SI-NETs from a single referral center (2007-2023) were prospectively collected. Patients were divided into three groups: non-metastatic (M0) and metastatic with primary tumor-related symptoms (MS) or metastatic asymptomatic (MA). Kaplan-Meier curves for overall survival (OS) and event-free survival (EFS) were generated and compared by group. Univariate and multivariable Cox regression analyses were performed to assess the significance of risk factors.

Results: Of 147 patients, 53 were M0, 23 were MS, and 71 were MA. Median follow-up was 26 months. The 5- and 10-year OS estimates were 100% and 100% in M0 patients, 82 and 21% in MS patients, and 89 and 80% in MA patients, respectively (p < 0.001). Median EFS was 91 months overall and 43,126 months and not reached for the MS, MA, and M0 groups, respectively (p < 0.001). In multivariable analysis, MS (hazard ratio [HR] 3.92, 95% confidence interval [CI] 1.71-9.52), functioning tumors (HR 1.98, 95% CI 1.03-3.81), and G2 grade (HR 3.20, 95% CI 1.64-6.85) were associated with a shorter EFS.

Conclusions: In this large retrospective series, the MS group had a significantly worse OS and EFS compared with M0 and MA. This finding suggests that prophylactic PTR might benefit SI-NET patients with unresectable liver metastases, as symptom development could impair long-term prognosis after surgery.