The predictive value of the systemic inflammation-nutrition index for treatment response and prognosis in patients with locally advanced gastrointestinal stromal tumors receiving neoadjuvant imatinib therapy: a dual-center retrospective cohort study.

Background: Although systemic inflammation- and nutrition-related indices have demonstrated predictive value for treatment response and prognosis in various malignancies, their role in locally advanced gastrointestinal stromal tumors (LA-GIST) undergoing neoadjuvant imatinib therapy (NIT) remains unclear.

Objectives: To evaluate the predictive value of the Systemic Inflammation-Nutrition Index (SINI) for pathological response and prognosis in patients with LA-GIST receiving NIT.

Designs: A retrospective, two-center study was conducted to evaluate the prognostic value of high pathological response, and to develop a nomogram incorporating SINI for predicting high pathological response in patients with LA-GIST undergoing NIT.

Methods: A retrospective analysis was performed on 200 patients with LA-GIST receiving NIT. Least Absolute Shrinkage and Selection Operator regression was used to construct the SINI from key hematological markers and to evaluate its association with relapse-free survival (RFS). A nomogram for predicting high response was established based on independent predictors identified by multivariate analysis, and the performance and prognostic values were validated in an external cohort.

Results: High response was independently associated with improved 5-year RFS. The 5-year RFS showed a significant stepwise gradient across the low-, medium-, and high-SINI groups (46.0% vs 75.3% vs 94.8%, all p < 0.05). SINI independently predicted high response. A nomogram incorporating preoperative imatinib duration, tumor size, and SINI demonstrated good discrimination in both the training and validation cohorts (area under the curve = 0.798 and 0.849, respectively), with well-fitted calibration curves and favorable net clinical benefit per decision curve analysis. Patients predicted to have a low response showed significantly shorter RFS than those with a high response (p < 0.01).

Conclusion: The SINI is an effective predictor of pathological response and prognosis in LA-GIST patients receiving NIT. The validated nomogram offers a practical tool for individualized treatment decision-making.