Association between wildfire-dominated PM _2.5 exposure and non-small cell lung cancer survival in California.

10520 Background: Wildfire emissions include hazardous constituents, including fine particulate matter ≤2.5 μm in diameter (PM 2.5 ). PM 2.5 exposure is associated with increased risk of lung cancer. However, the impact of wildfire-dominated PM 2.5 exposure on survival after non-small cell lung cancer (NSCLC) diagnosis is unknown. Methods: We identified all patients diagnosed with NSCLC in the California Cancer Registry between 2017-2020. Daily PM 2.5 was estimated over the same period by random forest regression fusing official air quality monitoring, satellite observations, meteorological modeling, predictive smoke modeling, and low-cost sensors, producing a consensus estimate of PM 2.5 over a 1-square kilometer grid across California. We quantified PM 2.5 exposure by averaging daily PM 2.5 in the 12 months after NSCLC diagnosis based on home address at time of diagnosis. Adjusted cox-proportional hazards regression was used to estimate the hazard ratio (HR) for cancer-related death associated with PM 2.5 exposure following NSCLC diagnosis overall and stratified by smoking status and stage at diagnosis. We adjusted for patient demographics, comorbidity, body mass index, rural residence, and COVID-19 time-period. Results: Among 18,585 patients with NSCLC, the mean age was 70.4 years (standard deviation [SD] 10.5) and the mean PM 2.5 concentration was 9.8 μg/m 3 (SD 2.0). Higher mean daily PM 2.5 in the 12 months after NSCLC diagnosis was associated with 20% increased hazard of cancer-related death (Table). There was a 55% increase in hazard of cancer-related death associated with PM 2.5 among patients with stage IV disease and no prior smoking use (Table). Notably, patients with Stage IV disease with former or current tobacco use who received immunotherapy had improved cancer-specific survival with more days of high PM 2.5 concentration (i.e., days with PM 2.5 ≥55 μg/m 3 ), HR=0.79, 95% confidence interval 0.66-0.94. Conclusions: In this large population-based NSCLC cohort, wildfire-dominated PM 2.5 exposure after diagnosis was independently associated with increased risk of cancer-related death. The improved survival among patients with Stage IV disease with a smoking history treated with immunotherapy warrants additional investigation. As the size and frequency of wildfires increases, our findings have important public health and clinical implications for patients with NSCLC. Hazard ratio (HR) for cancer-related death associated with PM 2.5 concentration after NSCLC diagnosis. Number of Patients Number of Cancer-Related Deaths Cancer-Related Death HR (95% confidence interval) Total cohort 18,585 6,097 1.20 (1.05-1.37) No prior tobacco use 5,059 1,565 1.36 (1.04-1.78) Former or current tobacco use 13,526 4,532 1.17 (1.01-1.36) Stage IV, no prior tobacco use 2,198 1,079 1.55 (1.12-2.16) Stage IV, former or current tobacco use 3,783 2,097 1.09 (0.87-1.36)