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


METHODS
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.


RESULTS
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.


CONCLUSIONS
Occupational exposures and family history of cancer with young onset were important risk factors among never smokers.
Brenner
Darren R
DR
Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, 60 Murray St, Toronto M5T3L9, Canada.
Hung
Rayjean J
RJ
Tsao
Ming-Sound
MS
Shepherd
Frances A
FA
Johnston
Michael R
MR
Narod
Steven
S
Rubenstein
Warren
W
McLaughlin
John R
JR
D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D016902:Air Pollution, Indoor / Q000009:adverse effects; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D005820:Genetic Testing; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D016017:Odds Ratio; D009864:Ontario / Q000453:epidemiology; D010375:Pedigree; D012140:Respiratory Tract Diseases / Q000150:complications / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects; D014504:Urban Health; D055815:Young Adult
D014028:Tobacco Smoke Pollution