Familial aggregation of lung cancer in a high incidence area in China

Abstract

To investigate whether lung cancer clusters in families in a high incidence county of China, an analysis was conducted using data on domestic fuel history and tobacco use for family members of 740 deceased lung cancer probands and 740 controls (probands' spouses). Lung cancer prevalence was compared among first-degree relatives of probands and of controls, taking into account various factors using logistic regression and generalised estimating equations. First-degree relatives of probands, compared with those of controls, showed an excess risk of lung cancer (odds ratio (OR) ¼ 2.05, 95% confidence interval (CI): 1.68 -2.53). Overall, female relatives of probands had a greater risk than did their male counterparts, and the risk was 2.90-fold for parents of probands as compared with parents of spouses. Female relatives of probands had 2.67-fold greater risk than female controls. Lung cancer risk was particularly marked among mothers (OR ¼ 3.78, 95% CI: 2.03 -7.12). Having two or more affected relatives was associated with a 2.69 -5.40-fold risk increase. The risk elevation was also found for other cancers overall. Results confirm previous findings of a genetic predisposition to lung cancer, and also imply that lung cancer may share a genetic background with other cancers. British Journal of Cancer (2005) Lung cancer has been the leading cause of cancer death in China, but is particularly high in Xuan Wei County, Yunnan Province, China. In this rural county (population about 1.2 million), more than 95% of people are farmers. Tobacco smoking is common in males (40% or more), but rare in females (less than 0.1%). Lung cancer mortality is five times the national average and among the highest in China, yet females despite almost all being nonsmokers have the highest rate in China (eight times the national female average). It is unusual to find similar male and female lung cancer mortality rates (27.7 and 25.3 per 100 000, respectively) as in Xuan Wei County (Mumford et al, 1987).Cigarette smoking has long been established as the predominant risk factor for lung cancer (Doll and Peto, 1978; IARC, 1986). Although an aetiological link between lung cancer mortality and domestic smoky coal use (polycyclic aromatic hydrocarbons) has been shown, the causes of lung cancer in Xuan Wei County have remained unexplained (Mumford et al, 1987;He et al, 1991). Host susceptibility factors, however, have not been explored there. Several studies have reported a slight increase of risk for relatives of lung cancer cases (Tokuhata and Lilienfeld, 1963;Mulvihill, 1976;Ooi et al, 1986;Bromen et al, 2000). Some of these, however, were limited to special groups such as nonsmokers or women, and this may have contributed to the different risks obtained (Schwartz et al, 1996;Wu et al, 1996;Brownson et al, 1997;Kreuzer et al, 1998;Pools et al, 1999). We have used improved modelling techniques to test the hypothesis that in Xuan Wei County, lung cancer cases are more likely than controls to have an affected relative. MATERIALS AND METHODS Study p...

Family history of cancer and nonmalignant lung diseases as risk factors for lung cancer

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