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I I I I I 1 I 1 I I I I I I I I I A CASE-CONTROL STUDY OF CHILDHOOD AND ADOLESCENT HOUSEHOLD PASSIVE SMOKING (PS) AND THE RISK OF FEMALE LUNG CANCER Wane Fu-lin¢*, Edgar J. Love** and Dai Xu-dong* * Heilongjiang Institute for Cancer Research, Harbin, China ** University of Calgary, Calgary, Canada Summary Backeround Exposure to environmental tobacco smoke, i.e., passive smoking (PS), has been a public health concern. This type of exposure has been suggested to be associated with many illnesses, such as cancer (especially lung cancer), cardiovascular disease, respiratory system signs and symptoms, etc. However, how to measure this exposure and its effects on health remains a key issue. Most previous studies estimated PS from only the husband or the spouse, which is far from accurate. More importantly, the effects of early life exposure to tobacco smoke on health during adulthood have not received much attention. Only a few studies have considered the importance of exposure to tobacco smoke in early life on risk of cancer in adulthood; several studies did not find any association between lung cancer and nonsmoking women exposed to tobacco smoke during childhood. Methods This study, using household exposure to tobacco smoke as an estimate of PS, was done to evaluate the risk of female lung cancer from PS, and focused especially on exposure during childhood and adolescence. The 1:1 paired case-control study was conducted in Harbin, China during 1985-87. We personally interviewed 114 female primary lung cancer cases, aged 30 to 69 years, and their hospital- based controls, using an established questionnaire. The controls were noncancer patients, selected from the same hospital as the cases, and matched for age (± 5 years), residential area and lifetime smoking status. There were 59 pairs who smoked and 55 pairs who never smoked. Information on PS was collected by residence for each of the following five periods: 0-6, 7-14, 15-22, 23-30 and 31-69 years. Results We found that the risk of female lung cancer in relation to PS varied by exposure period and by sources of sidestream smoke. For the "0-14 years" exposed group, the exposure was mainly from parents. A higher percentage of the cases had exposure from mothers (38.5 %) than the controls (26.4%). For the older age exposed group, husbands were the major source of sidestream smoke and accounted for more than two-thirds of the exposure for both cases and controls. Further analyses show that when exposed under the age of 14 years, the risk of lung cancer was significantly increased for household exposure to maternal smoking (odds ratio, OR=2.70, 95% CI=1.49-4.88), but not for exposure to paternal smoking (OR= 1.40, 95% CI= 0.79-2.50). The risk was the highest in the group who were exposed under the age of seven (OR=3.46, 95 % CI=1.80-6.65), but was also significant when exposed at ages 7-14 (OR=3.08, 95% CI=1.62-5.57) and 15-22 (OR=3.10, 95% CI=1.52-6.31). Moreover, as long as exposure occurred under the age of 23 years, the OR increased with amount of exposure to I

passive smoking (P<0.001). No significant differences were found between the cases and controls when exposure was at ages 23-30 and 31-69 years. When stratified by smoking status, the risk was significantly increased for the ever-smokers who were exposed at ages 22 or younger, likewise, the risk also increased for the nonsmokers who were exposed under the age of 15 years. Conclusions The findings of this study suggest that (1) household passive smoking, particularly that occurring during childhood, increases the risk of female lung cancer, and (2) the effects of PS on lung cancer, and possibly on other health conditions, should be assessed by different periods of exposure. -2- N 0 tp ~ ~ w 0 CO (D I I I I I I I I I I I I I I I I I I I