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Clin Lung Cancer. 2018 Sep;19(5):e539-e550. doi: 10.1016/j.cllc.2018.03.013. Epub 2018 Mar 17.

A Decade of Never-smokers Among Lung Cancer Patients-Increasing Trend and Improved Survival.

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Division of Medical Oncology, National Cancer Centre, Singapore. Electronic address:
Division of Clinical Trials and Epidemiological Sciences, National Cancer Centre, Singapore.
Division of Medical Oncology, National Cancer Centre, Singapore.
Saw Swee Hock School of Public Health, National University of Singapore, Singapore.



It is not known whether clinicopathologic characteristics, treatment, and survival of never-smokers among lung cancer incident cases have changed over time. We assessed the trend and overall survival (OS) of these patients within our institution during a 10-year period.


We reviewed 2 cohorts of non-small-cell lung cancer patients with a diagnosis from 1999 to 2002 and from 2008 to 2011. The patient characteristics and OS were compared by smoking status within each cohort and between the 2 cohorts over time.


Of the 992 patients in the 1999-2002 cohort and the 1318 patients in the 2008-2011 cohort, 902 and 1272 had a known smoking status, respectively. The proportion of never-smokers increased from 31% in 1999-2002 to 48% in 2008-2011 (P < .001). Within both cohorts, the differences in characteristics among never-, former-, and current-smokers have remained largely constant over time. A greater proportion of never-smokers had Eastern Cooperative Oncology Group performance status 0 to 1 and adenocarcinoma. The median OS increased from 15.5 months in 1999-2002 to 24.9 months in 2008-2011 (P = .001) for never-smokers, 12.3 to 15.9 months (P = .150) for former-smokers, and 10.5 to 13.9 months (P = .011) for current-smokers. The larger survival improvement among never-smokers was likely accounted for by the larger increase in never-smokers who were treated with tyrosine kinase inhibitors and pemetrexed over time.


We found an increasing trend of never-smokers among incident lung cancer cases and improved survival for these patients during a 10-year period. The documentation of smoking status in any national cancer registry is vital to estimate the true incidence of lung cancer among never-smokers over time.


Adenocarcinoma; Consortium; Non–small-cell lungcancer; Singapore; Smoking status

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