In advanced non-small cell lung cancer (NSCLC), factors such as susceptibility to epidermal growth factor receptor tyrosine kinase inhibitors with pathological subtype of adenocarcinoma, smoking history, and female gender are predictive. However, we need novel predictive markers as well as driver mutations for improved therapy choices. The present study aimed to investigate the prognostic significance of sarcopenia in lung adenocancer patients treated with erlotinib. Skeletal muscle index (SMI) was calculated using a single cross-sectional area of the muscle at the third lumber vertebra (L3, cm2)/(height × height) (m2), and this study was performed retrospectively. The median cut-off values of SMI for males (< 32.7 cm2/m2) and women (< 28.2 cm2/m2) were used to characterize sarcopenia. The cox-regression model was used to evaluate the predictive role of sarcopenia and other factors. The age range was 36 to 84 years, with a median of 56 years. The median progression-free survival (PFS) of the sarcopenic group was 38 weeks (95% CI = 21.3–54.6), while that of the non-sarcopenic group was 49 weeks (95% CI = 0–101.4; P = 0.053). Sarcopenia and the number of metastasis were the independent predictors of PFS in multivariate analysis, and there was no significant difference in disease control rate or overall survival between the sarcopenic and nonsarcopenic groups. We demonstrated that the presence of sarcopenia and the number of metastases are prognostic signs in NSCLC patients treated with erlotinib. Early detection of sarcopenia and appropriate patient management are crucial. We demonstrated that the existence of sarcopenia and multiple metastases is a prognostic sign in NSCLC patients treated with erlotinib. Early detection of sarcopenia and appropriate patient management are crucial.
