Nonlinear association between body mass index and overall survival in advanced NSCLC patients treated with immune checkpoint blockade

Background: We investigated the association of body mass index (BMI) modeled as a continuous variable with survival outcomes in advanced non-small cell lung cancer (NSCLC) patients treated with immune checkpoint inhibitors (ICI).

Methods: We performed a single-institution retrospective analysis of consecutively diagnosed locally advanced or metastatic NSCLC patients treated with single-agent ICI in the first line or recurrent setting. The primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS) and objective response rate (ORR). BMI was modeled using a four-knot restricted cubic spline. Multiple Cox regression was used for survival analysis.

Results: Two hundred patients were included (female 54%; never smoker 12%). Adenocarcinoma was the most common histology (61%). Median age was 67 years, median BMI was 25.9 kg/m², and 65% of patients had Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-1. On multivariable analysis, only BMI and ECOG PS were independently associated with OS (p < 0.01). Mortality risk decreased as the BMI increased from 20 to 30 kg/m² (HR 0.49, 95% CI 0.28-0.84); however, it was reversed as the BMI surpassed ~ 30 kg/m². Compared to ECOG PS ≥ 2, patients with ECOG PS of 0-1 had a longer OS (HR 0.42, 95% CI 0.28-0.63). Similar trends were observed with PFS and ORR, but the strength of the association was weaker.

Conclusion: We observed a nonlinear association between BMI and OS following treatment with ICI in advanced NSCLC. Risk of death increases at both extremes of BMI with a nadir that exists around 30 kg/m².