RE: Smoking History as a Potential Predictor of Immune Checkpoint Inhibitor Efficacy in Metastatic Non-Small Cell Lung Cancer

We read with interest the article in this issue of the Journal by Wang et al. (1), whose study evaluated the association between smoking exposure and treatment response, progression-free survival, and overall survival in patients with advanced nonsmall cell lung cancer treated with immune checkpoint inhibitor (ICI) monotherapy. The authors provided quantitative evidence that smoking pack-years of tobacco was independently prognostic above clinicopathological characteristics, tumor mutation burden, and PD-L1 expression for response and survival outcomes within a cohort of 644 patients. In this correspondence, we highlight 2 aspects that require further comment: 1) the authors statements on the potential for smoking exposure to inform ICI efficacy, in the absence of a control arm, and 2) the potential importance of smoking pack-years vs smoking status
(ie, never, former, or current) to future research.