Clinical impact of skeletal muscle area in patients with non-small cell lung cancer treated with anti-PD-1 inhibitors

Purpose: The aim of this study was to elucidate the clinical impact of skeletal muscle area (SMA) in patients with non-small cell lung cancer (NSCLC) treated with anti-programmed cell death-1 (PD-1) inhibitors. Methods: Univariate and multivariate analyses were performed on data of 103 patients with advanced or recurrent NSCLC treated with anti-PD-1 inhibitors. The SMA was measured at the level of the third lumbar vertebral (L3) on computed tomography images using OsiriX software (32-bit, version 5.8; OsiriX, Geneva, Switzerland). The L3 muscle index (cm²/m²) was defined as the SMA (cm²) at the L3 level divided by the height (m) squared. Results: L3 muscle index ^Low was an independent predictor of both progression-free (P = 0.0399) and overall survival (P = 0.0155). Moreover, the disease control rate was significantly lower in the L3 muscle index ^Low group (49.0% [25/51]) than in the L3 muscle index ^High group (73.1% [38/52]; P = 0.0117). However, there was no significant difference between the response rates of the L3 muscle index ^Low group (21.6% [11/51]) and L3 muscle index ^High group (32.7% [17/52]; P = 0.2031). Conclusions: L3 muscle index ^Low is an independent predictor of worse outcomes in NSCLC patients treated with anti-PD-1 inhibitors.