Significance of CT-Derived Sarcopenia Using L3 Skeletal Muscle Index in Lung Cancer Patients: A Prognostic Retrospective Study

Abstract

Introduction:
Sarcopenia, a progressive loss of skeletal muscle mass and strength, is increasingly recognized as a negative prognostic factor in cancer patients. In lung carcinoma, sarcopenia often coexists with cachexia and systemic inflammation, contributing to reduced treatment tolerance and poor survival outcomes. Computed tomography (CT)-based measurement of the skeletal muscle index (SMI) at the L3 vertebral level is a validated and non invasive method for assessing sarcopenia.
Aim and Objective:
To evaluate the prognostic significance of CT-derived sarcopenia using L3 skeletal muscle index (L3SMI) and its correlation with survival in lung cancer patients.
Materials & Methods:
This retrospective cohort study was conducted in the Department of Radiodiagnosis, Govt. Kilpauk Medical College Hospital, from October 2020 to September 2021. Fifty lung cancer patients aged over 18 years who underwent CT including the L3 level within two months of diagnosis were included. Sarcopenia was defined as L3SMI <41 cm2/m2 in females and <53 cm2/m2 in males. Clinical and laboratory data were collected and survival
outcomes were analyzed using Pearson correlation and ANOVA.
Results:
Out of 50 patients, 29 (58%) were sarcopenic, and 23 of them died during a follow-up period of 6–12 months. A strong positive correlation was observed between low L3SMI and mortality (r = 0.726, p < 0.001). Sarcopenia also showed a strong negative correlation with ECOG performance status (r = –0.824). Advanced cancer stage and low serum albumin levels were significantly associated with increased mortality.
Conclusion:
CT-derived L3SMI is an effective predictor of mortality in lung cancer patients. Early identification of sarcopenia allows for timely interventions to improve clinical outcomes and survival.