Radiomics-based risk prediction: survival in sarcopenic gastrointestinal and genitourinary cancer cohorts using a population-specific sarcopenia definition

Objective This study demonstrated that the recently proposed Asian (Japanese)-cohort-based skeletal muscle index (SMI) definition (< 36.2 cm²/m² cm 2 / m 2 for males and < 29.6 cm²/m² cm 2 / m 2 for females), along with other factors such as radiomic and clinical variables, could improve risk categorization for survival in sarcopenic, gastrointestinal (GI), and genitourinary (GU) cancer patients. Materials and methods This retrospective study involved 2,015 patients who underwent major surgery at our institution between 2006 and 2018. From the axial CT image of the L3 vertebral region, the skeletal muscle was segmented to calculate the SMI values. 646 radiomic features were extracted from the image, and the Boruta algorithm was used to identify the most pertinent features. The final set of features consisted of these features and clinical variables. The dataset was split into training and testing sets comprising 1,512 patients (75%) and 503 patients (25%), respectively. Four models were evaluated in this study: (1) random survival forest (RSF)-based radiomic model, (2) Cox proportional hazard-based model, (3) Asian (Japanese)-specific SMI definition-based model, and (4) integrated model, which combines experiments (2) and (3). The Kaplan–Meier (KM) curves, log-rank tests, and Harrell’s concordance index (C-index) were computed to assess the predictive performance of the models. Results The integrated model achieved the highest performance in terms of C-index (0.760, 95% CI: 0.686–0.835) among all other models. Survival stratification was statistically significant across all the experiments ( p < 0.0001). Conclusion This work demonstrates the efficacy of utilizing recently proposed Japanese population-based SMI definition values to optimize risk stratification for sarcopenic patients. Key Points Question Can population-specific sarcopenia definitions, clinical variables, and CT muscle radiomics together improve overall survival risk stratification in patients with gastrointestinal and genitourinary cancers? Findings In this cohort of 2,015 patients, combining sarcopenia, clinical variables, and CT muscle radiomics yielded an overall survival C-index of 0.760. Relevance statement The incorporation of the Asian (Japanese)-specific skeletal muscle index definition improves risk stratification for the survival of sarcopenic cancer patients when combined with an imaging-based approach, such as radiomics and other clinical parameters, highlighting the value of multimodal integration.