Predictive significance of thoracic skeletal muscle nutritional status for radiotherapy survival in elderly patients with esophageal squamous cell carcinoma

The prognosis of patients with esophageal cancer is associated with nutrition. The aim of the present study was to investigate the effect of thoracic status on the prognosis of elderly patients with esophageal squamous cell carcinoma (ESCC) following radiotherapy. A retrospective analysis was performed of 123 elderly patients who underwent radiotherapy for ESCC and were admitted to The Affiliated Hospital of Xuzhou Medical University (Xuzhou, China) between October 2018 and October 2021. General clinical data and hematological data of the patients were collected before radiotherapy, with CT delineation of the 10-segment thoracic skeletal muscle volume by radiotherapy. The 10th thoracic vertebra level skeletal muscle volume index (T10 SMVI)=T10 skeletal muscle volume (cm³)/height² (m²). By dividing the patients according to the optimal cutoff value (using X-tile 3.6.1) into the T10 sarcopenia group and the T10 non-reduced skeletal muscle group (T10 non-sarcopenia group), intergroup comparisons were performed. The area under the curve was calculated from the receiver operating characteristic curve (ROC) to assess the prediction ability of T10 SMVI, the prognosis nutrition index (PNI) and the geriatric nutrition risk index (GNRI) for survival outcomes. Survival curves were drawn using the Kaplan-Meier method, and risk factors affecting progression-free survival (PFS) and overall survival (OS) were analyzed by a Cox proportional hazards model. The results of the comparisons between the groups showed significant differences between the two groups in terms of age, body mass index, tumor site, Tumor-Node-Metastasis stage, initial treatment, hemoglobin level, GNRI and albumin level. The T10 sarcopenia group exhibited significantly lower PFS and OS rates compared with the T10 non-sarcopenia group at all time points. The 1- and 3-year PFS rates of the T10 sarcopenia group compared with those of the T10 non-sarcopenia group were 50.8 and 73.4%, and 15.3 and 37.5%, respectively. The median PFS times for the two groups were 12.0 and 24.7 months, respectively. The 1- and 3-year OS rates were 81.4 and 95.3%, and 25.4 and 64.1%, respectively. The median OS time was 22.1 months in the T10 sarcopenia groups and not reached in the T10 non-sarcopenia group. ROC curve analysis showed that T10 SMVI, PNI and GNRI all predicted the long-term survival of elderly patients with ESCC following radiotherapy, and that the predictive efficacy of T10 SMVI was higher than that of the hematological nutritional indicators PNI and GNRI, and was an independent influencing factor of OS. In conclusion, T10 SMVI can quantify the nutritional status of thoracic skeletal muscle and is more efficient than PNI and GNRI for predicting the prognosis of elderly patients with ESCC, providing a reference for clinical evaluation of skeletal muscle dystrophy. The present study pioneers the application of T10 SMVI derived from radiotherapy planning CT, offering a cost-effective, standardized method to assess skeletal muscle nutrition in elderly patients with ESCC.