Risk factors associated with lung cancer in Hong Kong

Abstract

The purpose of this study was to investigate the risk factors associated with lung cancer in Hong Kong. Three hundred and thirty-one histologically or cytologically proven consecutive cases of lung cancer and the same number of in- and out-patients without cancer matched for age and sex were recruited for this study using a detailed questionnaire completed by a trained interviewer. Smoking was the most important risk factor associated with lung cancer but the attributable risk (AR) was estimated to be 45.8% in men and 6.2% in women, considerably lower compared with those estimated in early 1980s. In addition, among women, exposure to environmental tobacco smoke (ETS) at work±at home and lack of education, were independent risk factors for lung cancer with adjusted odds ratio (OR) 3.60, (95% confidence interval (CI) 1.52–8.51) and OR 2.41 (95% CI 1.27–4.55), respectively. Among men, exposure to insecticide/pesticide/herbicide, ETS exposure at work or at home, and a family history of lung cancer and were independent risk factors with adjusted OR 3.29 (95% CI 1.22–8.9, OR 2.43, 95% CI 1.24–4.76 and OR 2.37, 95% CI 1.43–3.94, respectively). Exposure to incense burning and frying pan fumes were not significant risk factors in both sexes. A moderate or high consumption of fat in the diet was associated with increased risk in men but decreased risk in women. The results of this study suggested that as the prevalence of smoking declined, the influence of smoking as a risk factor for lung cancer decreased even further. Moreover, the contribution of other environmental, occupational and socioeconomic factors may be more apparent as etiological factors for lung cancer in a population with relatively high lung cancer incidence but low AR from active smoking.

Introduction

Lung cancer is the most common cause of cancer mortality in Hong Kong and worldwide. In 1999, the incidence of lung cancer in Hong Kong was 58.3/100 000 in men and 23.2/100 000 in women [1]. While cigarette smoking is the most important cause for lung cancer in both men and women in the Western world, the attributable risk (AR) of cigarette smoking was found to be only 35.8% in women in Hong Kong in 1985 [2]. The etiologic or risk factors associated with lung cancer in nonsmoking women are not entirely clear. Exposure to passive smoke, occupational exposures, air pollution, and dietary factors have been implicated. However, the increased risk for lung cancer due to exposure to environmental tobacco smoke (ETS) was found to be small in Hong Kong; with the odds ratios (OR) in two different studies found to be approximately 1.6 [2], [3]. There have been many studies investigating the relation between nutrition and lung cancer [4], [5], [6], [7], [8], [9], [10], [11]. After adjusting for smoking, most of the observational studies suggest that increased vegetable and fruit intake is associated with a lower risk for lung cancer in both men and women. In Hong Kong, Koo et al. from a study conducted in the early 1980s [5] reported that higher consumption of leafy green vegetables, carrots, bean curd, fresh fruits and fresh fish was associated with a lower risk for adenocarcinoma in nonsmoking women.

There has been a slow decline in the incidence of lung cancer in Hong Kong during the past two decades [1]. The purpose of this study was to investigate the risk factors associated with lung cancer in Hong Kong and whether risk factors have changed during the past two decades since lifestyle, nutrition, and exposure to environmental carcinogens have changed in Hong Kong.