Association of Systemic Inflammatory Response Index and Prognostic Nutritional Index Scores with Sarcopenia in Patients with Metastatic Gastric Cancer

<i>Background and Objectives:</i> Sarcopenia is frequently observed in cancer patients and is associated with short survival. In this study, the aim was to research the sarcopenia risk factors, the correlation of sarcopenia with inflammatory biomarkers, and the prognostic significance of sarcopenia and inflammation markers in patients with metastatic gastric cancer. <i>Material and Method</i>: The study included 177 patients diagnosed with metastatic gastric cancer attending Dokuz Eylül University Faculty of Medicine (DEUFM) Medical Oncology clinic from 2016 to 2022. The skeletal muscle area at L3 vertebral level was identified on abdominal computed tomography (CT) images, and the skeletal muscle index (SMI, cm²/m²) was calculated. Additionally, PLR, MLR, NLR, dNLR, SIRI, SII, PIV, PNI, CAR, and LAR were assessed among systemic inflammatory biomarkers. Cut-off values were determined with ROC curve analysis. Survival analyses were performed with the Kaplan-Meier method, and risk factors were investigated with Cox regression analysis. For all statistical analyses, <i>p</i> < 0.05 was accepted as significant. <i>Results:</i> Among patients, 71.8% were identified to have sarcopenia. Significant levels of difference were identified for median SIRI, NLR, MLR, PLR, SII, PNI, and dNLR values between patients with and without sarcopenia (<i>p</i> < 0.05). The sarcopenia risk was assessed between groups created according to the cut-off values for inflammation markers. Univariate regression analysis found that SIRI, PIV, NLR, MLR, PLR, SII, PNI, and dNLR were statistically significant (<i>p</i> < 0.05). Multivariate analysis identified SIRI and PNI as independent risk factors. For all patients, median overall survival was identified to be 12.4 ± 0.8 months (CI 95%, 10.8-13.9). For patients with sarcopenia, overall survival duration was 11.5 ± 0.8 months, while survival duration for patients without sarcopenia was 17.5 ± 4.6 months (<i>p</i> = 0.010). Elevation in the inflammatory biomarkers of SIRI, NLR, SII, LAR, and CAR and low PNI values appear to be associated with short survival (<i>p</i> < 0.05). <i>Conclusions:</i> In this study, sarcopenia was frequently observed in patients with metastatic gastric cancer and sarcopenia was associated with shorter survival. A significant correlation was observed between sarcopenia and inflammatory biomarkers, with SIRI and PNI identified to be independent risk factors for sarcopenia. Our study emphasizes the prognostic importance of sarcopenia and inflammatory markers for the management of patients with metastatic gastric cancer.