Independent association of metabolic tumor response on FDG-PET with pulmonary toxicity following risk-adaptive chemoradiation for unresectable non-small cell lung cancer: Inherent radiosensitivity or immune response?

•Mid-treatment decline in tumor FDG avidity was independently associated with increased risk of pneumonitis.•FDG PET may serve as a marker of both tumor response and toxicity risk to personalize treatment regimens.•Pre-treatment biomarkers for pneumonitis were disproportionately from immunology pathways.