Open Access Highly Accessed Research article

Lung cancer risk in never-smokers: a population-based case-control study of epidemiologic risk factors

Darren R Brenner12, Rayjean J Hung12, Ming-Sound Tsao34, Frances A Shepherd34, Michael R Johnston34, Steven Narod235, Warren Rubenstein6 and John R McLaughlin127*

Author Affiliations

1 Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, 60 Murray St., Toronto, M5T 3L9, Canada

2 Dalla Lana School of Public Health, University of Toronto, 155 College St., Toronto, Ontario, M5T 3M7, Canada

3 Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontatrio, M5S 1A8, Canada

4 Princess Margaret Hospital, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada

5 Women's College Health Research Institute, 790 Bay Street, Toronto, Ontario, M5G 1N8, Canada

6 Mount Sinai Hospital Family Medicine Clinic, 60 Murray St., Toronto, M5T 3L9, Canada

7 Population Studies and Surveillance, Cancer Care Ontario, 620 University Ave. Toronto Ontario, M5G 2L7, Canada

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BMC Cancer 2010, 10:285  doi:10.1186/1471-2407-10-285

Published: 14 June 2010



We conducted a case-control study in the greater Toronto area to evaluate potential lung cancer risk factors including environmental tobacco smoke (ETS) exposure, family history of cancer, indoor air pollution, workplace exposures and history of previous respiratory diseases with special consideration given to never smokers.


445 cases (35% of which were never smokers oversampled by design) between the ages of 20-84 were identified through four major tertiary care hospitals in metropolitan Toronto between 1997 and 2002 and were frequency matched on sex and ethnicity with 425 population controls and 523 hospital controls. Unconditional logistic regression models were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI) for the associations between exposures and lung cancer risk.


Any previous exposure to occupational exposures (OR total population 1.6, 95% CI 1.4-2.1, OR never smokers 2.1, 95% CI 1.3-3.3), a previous diagnosis of emphysema in the total population (OR 4.8, 95% CI 2.0-11.1) or a first degree family member with a previous cancer diagnosis before age 50 among never smokers (OR 1.8, 95% CI 1.0-3.2) were associated with increased lung cancer risk.


Occupational exposures and family history of cancer with young onset were important risk factors among never smokers.