# Small Bowel Gastrointestinal Stromal Tumors: A 15-Year Cohort Study Focusing on Jejuno-Ileal Site-Specific Outcomes and Prognostic Factors

## TL;DR

This study examines long-term outcomes of small bowel GISTs, finding that ileal location, tumor size, and Ki-67 levels are linked to higher recurrence risk.

## Contribution

The study highlights the potential role of Ki-67 as a prognostic marker and the need for extended follow-up in certain small bowel GIST patients.

## Key findings

- Ileal tumors, larger size, and high Ki-67 levels were associated with higher recurrence risk.
- Some low-risk patients experienced recurrence more than 10 years after surgery.
- Patients with neurofibromatosis type 1 often had multiple jejunal tumors.

## Abstract

Small bowel gastrointestinal stromal tumors (GISTs) are rare; however, they are more aggressive than those in the stomach. Preoperative diagnosis is often challenging due to their submucosal origin, leading to diagnostic delay. This study analyzed 27 patients with tumors in the jejunum or ileum for 15 years to clarify long-term outcomes and risk factors. We found that tumors in the ileum, larger than 10 cm, and with high cell division or Ki-67 index were more likely to recur. Some patients developed recurrence more than 10 years after surgery, even when initially considered to have low risk. We also observed that patients with neurofibromatosis type 1 often had multiple tumors. Our findings indicate that prolonged follow-up may be warranted for selected patients and that Ki-67 could serve as an additional marker in risk assessment. These results are hypothesis-generating and should be interpreted with caution given the small sample size.

Background: Site-specific long-term outcomes, including neurofibromatosis type 1 (NF1), Ki-67 prognostic value, and very late recurrences of small bowel gastrointestinal stromal tumors (GISTs), remain inadequately defined. Methods: This retrospective cohort study investigated the clinical characteristics, diagnostic challenges, and long-term outcomes of patients with small bowel GISTs. This retrospective, single-center study (2008–2024) analyzed 27 consecutive patients (average age: 62.2 years) with jejunal/ileal GISTs. Clinicopathologic features, diagnostic yield of balloon-assisted enteroscopy (BAE), treatments, and outcomes were evaluated during a 10.2-year median follow-up period. Recurrence-free survival (RFS) and overall survival (OS) were estimated by Kaplan–Meier with log-rank testing. Ki-67 was assessed using MIB-1; a prespecified 5% cut-off was chosen based on prior evidence. Results: Tumor (mean size, 62.4 mm) sites included the jejunum (74.1%) and ileum (25.9%). NF1 was present in 3/27 (11.1%) patients, all with multiple jejunal tumors. Among the 14 patients who underwent BAE, biopsy was attempted in six and yielded a histological diagnosis in one (16.7%). Six patients had recurrence; two died from disease >10 years postoperatively. Five-year OS and RFS were 91.3% and 68.7%, respectively. Adverse RFS was associated with ileal location (p = 0.03), size ≥ 10 cm (p < 0.001), mitoses > 5/50 high-power fields (p = 0.002), and Ki-67 ≥ 5% (p < 0.001). One patient labeled low risk by conventional models had recurrence with Ki-67 = 10%. Another classified as low risk by conventional models experienced recurrence >10 years after surgery, with a Ki-67 index of 10%. Conclusions: Extended, risk-adapted surveillance may be reasonable for small-bowel GISTs, and it may be beneficial to incorporate Ki-67 (≥5%) into site-based risk stratification. These observations remain hypothesis-generating and require validation in larger, multicenter cohorts and prospective studies.