A Cohort Study On Risk Factors Of Lung Cancer Among Non-smoking Women In Urban Shanghai

【Objective】To explore the possible risk factors of lung cancer among non-smoking women based on an on-going prospective and population-based women cohort in urban Shanghai,and try to provide scientific evidences for the prevention and control of female lung cancer.【Methods】75,221 female study subjects aged 40 to 70 were recruited at the baseline survey of the Shanghai Women's Health Study(SWHS),a prospective women cohort study established during 1997 to 2000.In which,72,829 participants were non-smoking. They were actively followed up biennially since 2000.The information on demographic data,smoking,passive smoking,alcohol drinking,tea drinking,diet,physical activity, menstrual and reproductive history,chronic diseases of lung,residence history, anthropometric measures and so on were collected during 1997 to 2000.In which,the information on dietary and physical activity was assessed by means of two questionnaires which were validated during the baseline survey.The body mass index (BMI) and waist hip ratio(WHR) were calculated from the data of height,weight,waist and hip circumferences.The Cox proportional hazard regression model was used to estimate relative risks(RRs) and 95%confidence intervals(95%Cis) for the adjustment of some potential confounders.【Results】By end of 2007,673,256.60 person-years were followed for the cohort,and average 9.24 person-years per subject.271 incident cases of female lung cancer were diagnosed in the cohort among non-smoking study subjects.The cumulative incidence rate was 372.10/100,000 and the incidence density was 42.25 per 100,000 person-years. The baseline characteristics(mean±sd) of the non-smoking women are 51.15±8.37 years old for age,157.55±5.54 cm for height,59.58±8.89 kg for weight,24.00±3.42 kg/m² for body mass index(BMI),0.81±0.05 for waist-hip ratio(WHR),77.82±8.75cm for waist circumference(WC) and 7021.03±1687.11 kJ for energy intake,respectively. Compared to non-smoking females with WHR＜0.77,the RR and 95%CI for women with WHR≥0.84 were 1.50(95%CI:1.05-2.13) after adjustment for age,education and family income.The relative risks increased with the increasing of WHR.Compared to non-smoking females with WC＜72cm,the RR and 95%CI for women with WC≥83cm were 1.43(95%CI:1.01-1.94).The highest quartiles of baseline BMI experienced a 0.95 fold risk(95%CI:0.67-1.34) of lung cancer compared to their counterparts with lowest quartiles group.Compared to females who never drank,the RR and 95%CI for women who ever drank were 1.35(95%CI:0.85-2.10).The RR and 95%CI for women who drank tea were 0.76(95%CI:0.56-1.13) when compared to females who never drink tea. The RR and 95%CI for women with irregular menstruation were 1.29(95%CI:0.77-2.13) when compared to females whose menstruation was always regular.Compared to women who took oral contraceptives,the RR and 95%CI for women who didn't take were 0.99(95%CI:0.74-1.34).The RR and 95%CI for women with hormone replaced therapy were 0.96(95%CI:0.68-1.38) when compared to females who never use it.In the second inhabitancy,compared to women who used briquette when cook,the RR and 95%CI for women who didn't use were 1.41(95%CI:1.02-1.96).In the third inhabitancy,compared to women who felt the ventilation was good when cook,the RR and 95%CI for women who felt it's bad were 1.86(95%CI:1.14-3.20).No association was observed for the cooking oils and the risk of lung cancer among non-smoking women.The RR and 95%CI for women who often took part in exercise during teen-age were 0.62(95%CI:0.47-0.82) when compared to women who didn't do.Compared to women who ate fresh vegetables weekly,the RR and 95%CI for women who ate daily were 0.92(95%CI:0.53 -1.59).Compared to women who ate fresh fruits once or less a week,the RR and 95%CI for women who ate four times or more a week were 0.46 (95%CI:0.23-0.91).The RRs and 95%CIs for highest-versus-lowest quartile comparisons of the intakes of some nutrients were 0.68(95%CI:0.48-0.97) for retinol, 0.55(95%CI:0.36-0.86) for Vitamin B₂ and 0.77(95%CI:0.55-1.08) for Vitamin E, respectively.The RR and 95%CI for women with asthma and whose husbands smoked were 3.07(95%CI:1.50-6.28) when compared to women without asthma and whose husbands didn't smoke.If the data analysis was limited for subjects without asthma,the RR and 95%CI for women with tuberculosis and bronchitis were 2.45(95%CI:1.09-5.52) when compared to women who never diagnosed for diseases of tuberculosis or bronchitis.Compared to women who had no first degree relatives diagnosed with cancer, the RR and 95%CI for women who had two or more first degree relatives diagnosed with cancer were 1.89(95%CI:1.18-3.03).From the multivariate Cox regression model,age,WHR,asthma,breast fibroadenoma, family history of cancer,intake of smoked/salted products may be associated with the increased risk of lung cancer,and taking part in exercise during teen-age and intake of Vitamin B₂ may have protective effects against lung cancer among non-smoking women in urban Shanghai.【Conclusion】1.Abdominal obesity(higher WHR) may be associated with the increased risk of lung cancer in non-smoking women,and no relationship was observed between BMI and the risk of lung cancer among non-smoking women.2.No relationships were observed between alcohol consumption,tea drinking and the risk of lung cancer among non-smoking women.3.Indoor air pollution such as worse ventilation,burning briquette when cooked may have positive relations with the risk of lung cancer among non-smoking women.4.There was no relation between hormone replacement therapy,oral contraceptive, number of pregnancy and the risk of female lung cancer.5.There may be inverse relationship between participating in exercise regularly when teen-age and the risk of lung cancer among non-smoking women.But the women who often took part in any physical activities during last 5 years or last year have not been experienced the decreased risk of lung cancer.6.Frequent intake of fruits may be associated with reduced risk of lung cancer among non-smoking women,however,no relation was found between frequent vegetable intakes and decreased risk of lung cancer.There may be inverse association between more intakes of retinol,Vitamin B₂ or Vitamin E and decreased risk of lung cancer among non-smoking women.The relationship between dietary factors and the risk of lung cancer warrants further investigation.7.The diseases of tuberculosis and bronchitis may be associated with the increased risk of lung cancer among non-smoking women.Women who suffered from disease of asthma and her husband also smoked may have increased risk of lung cancer.8.Family history of cancer may be associated with increased risk of lung cancer among non-smoking women,especially for women who had two or more first degree relatives diagnosed with cancer.9.The results from multivariate analysis indicated that age,WHR,asthma,breast fibroadenoma,family history of cancer,intake of smoked/salted product were associated with increased risk while often participating in exercise during teen-age and intake of Vitamin B₂ were associated with reduced risk of lung cancer among non-smoking women.