Objective

Lung cancer in never smokers is the seventh leading cause of cancer-related death worldwide. As the main pathological subtype, lung adenocarcinoma (LUAD) in never smokers (LAINS) is increasingly becoming an important public health concern. We aimed to explore the clinicopathological features and prognostic factors of LAINS.

Methods

LUAD patients diagnosed pathologically in West China Hospital from January 2009 to December 2016 were divided into LAINS (who smoked less than 100 cigarettes in their lifetime) and LAIS. We performed long term follow-up of the patients, which was up to a maximum of ten years.

Results

Of 8,396 patients included, 4,987 were LAINS (59.4%) and 3,409 were LAIS (40.6%). The proportion of LAINS increased from 57.1% in 2009 to 62.7 % in 2016 (P=0.025). In LAINS, stage I patients increased year by year (P<0.001). In terms of clinicopathological features, LAINS were more likely to be female (P<0.001) and younger (P<0.001). The LUAD subtype tends to be MIA, lepidic predominant adenocarcinoma and invasive mucinous adenocarcinoma. For treatment, LAINS were more likely to receive surgery (56.4 % vs 45.9 %) and targeted therapy (31.8 % vs 22.8 %). For prognosis, smoking was the independent risk factors of LUAD patients. LAINS have the significant higher 1-, 3-, 5- and 10-year OS rates. TNM stages, surgery and targeted therapy were independent correlated with OS.

Conclusion

The epidemiological characteristics of LUAD in never smokers have changed, the proportion of non-smokers is on the rise. Among these, patients with stage I disease increased year by year. LAINS have different clinicopathological features and significant higher 1-, 3-, 5- and 10-year OS rates that LAIS.