Risk factors for lung cancer among Canadian women who have never smoked

Abstract

Risk factors for lung cancer among women who had never smoked were assessed in a case-control study of 161 newly diagnosed histologically confirmed cases and 483 population controls between 1994 and 1997 in eight Canadian provinces. Measurement included socio-economic status, smoking habits, alcohol use, diet, residential and occupational histories and exposure to environmental tobacco smoke (ETS). Dose–response associations were observed for consumption of tea, adjusted odds ratios (ORs) 0.6 (95% confidence interval (CI)=0.3–0.9) for 1–7 cups per week and 0.4 (95% CI=0.2–0.7) for ≥8 cups per week (P=0.0008), and smoked meat, adjusted ORs 1.3 (95% CI=0.8–2.3) for 0.5 slice per week and 2.1 (95% CI=1.1–4.0) for >0.5 slice per week (P=0.02). Regular use of shortening in cooking was also related to lung cancer. Increased ORs with borderline significance were found for total consumption of meat, eggs or French fries and fried potatoes. Passive exposure to ETS at home (or at work) may be associated with lung cancer risk among never-smoker women; the adjusted ORs were 0.7 (95% CI=0.2–2.3), 1.2 (95% CI=0.4–3.2), 1.5 (95% CI=0.5–4.0) for 1–16, 17–30, and 31 or more years of combined residential and/or occupational ETS exposure, respectively, with a similar pattern for smoker-years of ETS exposure.

Introduction

Lung cancer is the leading cause of cancer mortality for both males and females in Canada [1]. Cigarette smoking has been identified as a major risk factor in the development of lung cancer [2], [3]. However, for lung cancer not attributable to cigarette smoking, other risk factors of public health interest have recently been considered, including exposure to environmental tobacco smoke (ETS) [4], [5], [6], [7], [8], indoor air pollution from Chinese-style cooking [9], [10], occupational exposures [11], high consumption of saturated fat [12], pre-existing lung diseases [13] and family history of cancer [14], [15], [16]. Consumption of vegetables, fruit and β-carotene decrease the risk of lung cancer among non-smokers [12], [17], [18], [19], [20], [21]. In contrast to the many studies of smoking and lung cancer, only a few comprehensive studies have examined risk factors for lung cancer among non-smokers, and the etiology of lung cancer among non-smokers remains poorly understood [22].

Data from the National Enhanced Cancer Surveillance System (NECSS) are used here to examine the role of alcohol use, tea and coffee drinking, diet, exposure to ETS, and occupational exposure to chemicals on lung cancer risk among never-smoker women in Canada.