This retrospective cohort study examined whether long-term exposure to wildfire-related PM2·5 (versus non-wildfire PM2·5) worsens overall survival in patients aged ≥65 with SCLC or NSCLC, using SEER-Medicare data from 2006–2019 across the contiguous USA.
Each 1 μg/m³ increase in wildfire-related PM2·5 raised mortality risk by 7.8% (HR 1.0782, 95% CI 1.0641–1.0924), compared to 1.7% per 1 μg/m³ for non-wildfire PM2·5 (HR 1.0171, 95% CI 1.0149–1.0192); wildfire-related PM2·5 was estimated to cause ~696 excess deaths per year in this cohort versus ~3,465 for non-wildfire PM2·5.
- Residential zip code–level exposure estimates may not capture actual personal exposure, introducing measurement error. - Study is limited to Medicare enrollees aged ≥65, restricting generalizability to younger lung cancer patients. - Retrospective design cannot establish causality; residual confounding by unmeasured factors (e.g., indoor air quality, smoking history granularity) is possible.
Wildfire smoke is significantly more toxic per unit than everyday PM2·5 for lung cancer patients — clinicians should counsel older patients with lung cancer in wildfire-prone or downwind regions to use air filtration and limit outdoor exposure during smoke events. Policy and public health efforts to reduce wildfire smoke exposure in this vulnerable population are urgently needed.
