Clinical and oncological impact of muscle-related parameters in oesophagogastric cancer

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Introduction Oesophagogastric cancer remains a disease associated with poor survival rates. Assessing muscle mass and quality can help identify patients with reduced muscle mass (myopenia) and muscle fat infiltration (myosteatosis). Aim To assess body composition (muscle mass and muscle quality) in patients with oesophageal or gastric cancer, and to analyse clinical associations and oncological outcomes. Patients and Methods Patients diagnosed with oesophagogastric cancer between November 2019 and December 2023 were included in this retrospective study. Skeletal muscle index (SMI) and density (SMD) were assessed via CT scans at the L3 level. Myopenia and myosteatosis were defined according the Martin’s criteria: myopenia was defined in men by an SMI <43 cm²/m² (BMI <25) or <53 cm²/m² (BMI ≥25) and in women by an SMI <41 cm²/m²; myosteatosis was defined by an SMD <41 HU (BMI <25) or <33 HU (BMI ≥25). Due to high prevalence of myopia and myosteatosis, and the lack of standardised cut-offs in the literature, muscle mass and radiodensities were categorised into tertiles based on their distribution in our study population. The lowest tertile served as the reference group to allow assessment of potential gradient effects with adequate statistical power. Clinical parameters (age, BMI, albumin level, CRP – C-reactive protein, NLR – neutrophil-to-lymphocyte ratio and PLR – platelet-to-lymphocyte ratio) and oncological outcomes (OS – overall survival and PFS – progression free survival) were analysed. Results Among 161 patients (67.1% male, mean age 65.0 ± 12.8 years), 49.1% had oesophageal and 50.9% gastric cancer. Most had adenocarcinoma (64.6%) and 25% had metastases. Mean SMI and SMD were 45.1 ± 10.5 cm²/m² and 24.6 ± 9.6 HU respectively. Despite a normal median BMI (25.2 ± 5.53 kg/m²), myopenia and myosteatosis were prevalent (62.7% and 87.6%, respectively). Uni- and multivariate analyses showed that metastases were independently associated with poorer OS (HR 3.28 [95% CI 1.847-5.824], p < 0.001) and PFS (HR 3.14 [95%CI 1.896-5.210], p < 0.001). SMD and PLR ratio were independent predictors of OS (HR 0.95 [95%CI 0.918-0.992], p = 0.017 and HR 1.00 [95%CI 1.001-1.006], p = 0.005) and PFS (HR 0.96 [95%CI 0.934-0.998], p = 0.037 and HR 1.00 [95%CI 1.001-1.005], p = 0.002), whereas CRP was independently associated with OS only (HR 1.00 [95% CI 1.000-1.011], p = 0.036). Kaplan–Meier survival analysis showed that SMI was significantly associated with poorer OS and PFS : patients with higher muscle mass (upper two tertiles combined) had a higher median OS compared with those in the lowest tertile (NE vs. 18.0 months, HR 0.57 [95%CI:0.36-0.91], p = 0.0162). Similarly, PFS was significantly longer in patients with high muscle mass (25.9 vs. 13.5 months, HR 0.63 [95%CI: 0.42–0.96], p = 0.0281). SMD, on the other hand, was associated with reduced survival, with patients in the higher tertiles (lower muscle density) having a higher median OS than those in the lowest tertile (NE vs. 20.5 months, HR 0.54 [95%CI: 0.34-0.86]; p = 0.0089). No significant difference was observed for PFS. Interestingly, despite lower muscle density, patients with myosteatosis also had lower SMI (42.3 vs 52.6 cm²/m², p<0.0001). Conclusions This study highlights the high prevalence of myopenia and myosteatosis in oesophagogastric cancer patients, even among those with normal BMI. Low muscle mass was associated with poorer OS and PFS, whereas reduced muscle density was specifically linked to OS. The coexistence of myosteatosis and low SMI suggests that fat infiltration and muscle loss may reflect a common catabolic process in cancer patients. These results support the relevance of body composition assessment for improving risk stratification and informing oncological management.

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