Effect of household smoking exposure in childhood on lung cancer risk in Korea: A case-control study

Abstract

9598 Background: Smoking is the major cause of lung cancer and the duration rather than the amount of smoking has much greater impact on lung cancer risk. Thus, exposure to household smoking in childhood may be much more harmful than currently appreciated. We conducted this study to examine the impact of passive exposure to household smoking in childhood on the risk of lung cancer. Methods: Using a pre-tested interview questionnaire, we collected demographic and socioeconomic data and the information on smoking status, both personal and exposure to environmental smoking in childhood from 2499 patients (pts) who visited National Cancer Center (NCC) between 5/2002 and 7/2003. There were 699 lung cancer cases (M/F: 498/201), 854 non-cancer pts (M/F: 388/466) who visited NCC for other than cancer including those who had cancer prevention and screening evaluation (Control I) and 946 cancer pts (M/F: 344/602) other than lung cancer (Control II). Results: For male lung cancer cases, the proportion of lifetime non-smokers were only 7.2%, which was significantly (p<0.001) different from 15.0%, and 15.7% of the controls I and II. However, the corresponding figures for females were 86.1%, 86.0%, and 88.2%, respectively, which was not statistically significant. By univariate analysis, age, <12 years of education, low income, and rural residence in childhood were associated with higher risk of lung cancer. When the groups are stratified by age (<50 vs. 50+), paternal smoking was an important risk factor for the 50+ age group, both for females (OR=1.515, p=0.198; OR=1.781, p=0.043) and for males (OR=2.151, p=0.006; OR=1.711, p=0.044) as compared with controls I and II, respectively. There was also a trend toward increased risk with maternal smoking for young (< 50 yrs) smoking males (OR=3.861, p=0.013) as compared with control I. Spouse smoking was not associated with any increased risk in this analysis, even for the non-smoking females. Conclusions: While more in-depth analyses are needed, these results strongly suggest that environmental exposure to household smoking in childhood is an important risk factor for lung cancer development. (Supported by NCC Grant 0210040). Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration National Cancer Center, Goyang, Gyeonggi, Korea