CT assessed morphological features can predict higher mitotic index in gastric gastrointestinal stromal tumors

To investigate the correlation of the mitotic index (MI) of 1–5 cm gastric gastrointestinal stromal tumors (gGISTs) with CT-identified morphological and first-order radiomics features, incorporating subgroup analysis based on tumor size.

We enrolled 344 patients across four institutions, each pathologically diagnosed with 1–5 cm gGISTs and undergoing preoperative contrast-enhanced CT scans. Univariate and multivariate analyses were performed to investigate the independent CT morphological high-risk features of MI. Lesions were categorized into four subgroups based on their pathological LD: 1–2 cm (n = 69), 2–3 cm (n = 96), 3–4 cm (n = 107), and 4–5 cm (n = 72). CT morphological high-risk features of MI were evaluated in each subgroup. In addition, first-order radiomics features were extracted on CT images of the venous phase, and the association between these features and MI was investigated.

Tumor size (p = 0.04, odds ratio, 1.41; 95% confidence interval: 1.01–1.96) and invasive margin (p < 0.01, odds ratio, 4.55; 95% confidence interval: 1.77–11.73) emerged as independent high-risk features for MI > 5 of 1–5 cm gGISTs from multivariate analysis. In the subgroup analysis, the invasive margin was correlated with MI > 5 in 3–4 cm and 4–5 cm gGISTs (p = 0.02, p = 0.03), and potentially correlated with MI > 5 in 2–3 cm gGISTs (p = 0.07). The energy was the sole first-order radiomics feature significantly correlated with gGISTs of MI > 5, displaying a strong correlation with CT-detected tumor size (Pearson’s ρ = 0.85, p < 0.01).

The invasive margin stands out as the sole independent CT morphological high-risk feature for 1–5 cm gGISTs after tumor size-based subgroup analysis, overshadowing intratumoral morphological characteristics and first-order radiomics features.

Question How can accurate preoperative risk stratification of gGISTs be achieved to support treatment decision-making?

Findings Invasive margins may serve as a reliable marker for risk prediction in gGISTs up to 5 cm, rather than surface ulceration, irregular shape, necrosis, or heterogeneous enhancement.

Clinical relevance For gGISTs measuring up to 5 cm, preoperative prediction of the metastatic risk could help select patients who could be treated by endoscopic resection, thereby avoiding overtreatment.