Association of lung silica deposition with epidermal growth factor receptor-mutant lung cancer

Exposure to particulate matter ≤2.5 μm (PM2.5), which comprises various components, has been implicated in epidermal growth factor receptor (EGFR)-driven lung cancer development. The silica can be inhaled non-occupationally as PM2.5, particularly that derived from Asian dust in East Asia.

This retrospective cross-sectional study investigated consecutive patients with surgically resected lung adenocarcinoma tested for EGFR mutations during 2020-2022. Silica particles in the resected lungs were counted via polarized light microscopy. Patients were categorized into high- and low-silica groups according to the cutoff value of the number of silica deposits. We conducted receiver operating characteristic curve analysis for EGFR mutation status according to silica deposit levels. We compared EGFR mutation profiles and performed logistic regression model analysis.

Of the 174 patients, only three had an occupational silica-exposure history. The median numbers of silica deposits in 20 microscopic fields-of-view were 26.0 and 9.0 particles in patients with and without EGFR mutations, respectively (P < 0.001). EGFR mutations occurred in 66.7 % and 30.4 % of participants in the high- (n = 72) and low-silica groups (n = 102), respectively (P < 0.001). The Cochran-Armitage trend test showed a significant linear trend for higher silica deposition with a higher prevalence of EGFR mutations (P < 0.001). Multivariate analysis revealed that high silica deposition was independently associated with EGFR mutations (adjusted odds ratio, 3.20; 95 % confidence interval, 1.49-6.88; P = 0.003).

Silica can be deposited in the lungs even without occupational exposure and is associated with EGFR-mutant lung adenocarcinoma.