To investigate the association between progressive muscle loss and survival outcomes of patients with advanced-stage oral squamous cell carcinoma (OSCC) undergoing surgery and adjuvant (chemo)radiotherapy.
We analyzed the computed tomography (CT) scans of 155 patients with stage III-IVB OSCC at baseline, at simulation CT for radiotherapy, and at 3- and 9-months post-treatment. Skeletal muscle index (SMI) was measured using CT at the C3 vertebral level. The predictors of overall survival (OS) and recurrence-free survival (RFS) were evaluated using Cox regression models.
The median follow-up period was 75.0 months. Fifty-one patients (32.9%) developed recurrence, with the median time from the fourth CT to recurrence being 9.1 months. The SMI progressively decreased from baseline to simulation CT by 1.1% (p=0.006), to 3 months post-treatment by 5.1% (p<0.001), and to 9 months post-treatment by 15.6% (p<0.001) in patients developing recurrence. Patients without recurrence lost SMI at the simulation CT by 0.7% (p=0.001) and at 3 months post-treatment by 2.1% (p<0.001); their SMI returned to the baseline level at 9 months post-treatment. SMI changes were weakly correlated with changes in body mass index (BMI) (Spearman ρ, 0.13; p=0.11). In multivariate analysis, SMI changes (per 5% decrease) were independently associated with significantly worse OS (hazard ratio: 1.88, 95% confidence interval: 1.58-2.23; p<0.001) and RFS (hazard ratio: 1.89, 95% confidence interval: 1.61-2.20; p<0.001).
Progressive muscle loss was independently associated with worse survival outcomes in patients with stage III-IVB OSCC. Muscle loss might not be detected by changes in BMI.