Environmental Factors, DNA Repair Gene And Lung Cancer Risk

Lung cancer is the most common cancer and one of the most fatal dieases in Chinese population.Etiology of lung cancer is complicated and multifactor,and remained unclear.To explore the possible effect of smoking,indoor air pollution and DNA repair gene polymorphism on the development of lung cancer,especially the development of women lung cancer in north China,a case-control study was conducted which included 396 lung cancer cases and 465 normal residents as controls.The results are as following:1.In present study,it was confirmed that cigarette smoking was associated with elevated risk of lung cancer,while the associations varied among different histological types of lung cancer.Squamous cell carcinoma and small cell carcinoma possessed much closer relationship with smoking than adenocarcinoma(OR=5.01/OR=5.06/OR=2.73).The risks of lung cancer bviously elevated with increasing duration of cigarettes use, cigarettes per day,earlier age at which smoking started,as well as depth of inhalation. Smokers,whose sum consumption of tobacco was over 40 packyear could suffer 10 times of risk of lung cancer than nonsmokers.Furthermore,cigarettes without filter-tip might lead 6.4 times of lung cancer risk then filter-tip cigarettes done.2.Passive smoking was found related with higher risk of lung cancer,for both passive smoking at workplace and home.Besides,if passive smoking combined with active smoking,the risk would be greatly increased.Coal burning in cooking and warming, non-usage of ventilation equipment in kitchen,cooking times per week might associate with the elevated risk of lung cancer,especially the risk of adenocarcinoma.Furthermore, the indoor air pollution factors might possess much stronger association among female and adenocarcinoma,compared to male and other histological types of lung cancer.3.The concentration of small particles,including PM₁ and PM_2.5 might associate to passive smoking;the concerntration of particles,which larger than PM_2.5 might associate to coal buring.Besides of this,the usage of ventilation equipments might lead change of all kinds of particles.The concentration of PM₁ holds closer correlation to the risk of lung cancer than other paticles.4.Tea drinking might be in relation to the decreased risk of lung cancer,for both smokers or non-smokers.Light alcohol drinkers possessed significant decreased risk of lung cancer versus non-drinker,whereas the heavy drinkers have slightly increased risk of lung cancer.5.The polymorphisms of NER gene XPD codon 751 might be associated with susceptibility of lung cancer.Carrying Lys/Gln genotype might lead to borderline increased risk of adenocarcinoma(OR=1.59,95%CI:0.92-2.80),and the associate became significant among male,with the OR:2.50,95%CI:1.09-5.72.The polymorphism of NER gene ERCC 1 codon 118 might not have direct association with the susceptibility of lung cancer. Moreover,no significant interaction between this polymorphism and smoking was found in the development of lung cancer.6.The polymorphisms of BER gene XRCC1 codon 194 and codon 399 might be directly associated with the development of lung cancer.In detail,the homozygous genotype Trp/Trp of codon 194 could increase the risk of small cell carcinoma notably(OR=2.77), and the homozygous genotype Gln/Gln of codon 399 might cause remarkable higher risk of squamous cell carcinoma(OR=2.31).In the combined analysis with smoking status, nearly 8 times of odds risk and even higher risk were found in smokers who carry homozygous genotype of the two polymorphisms.Higher risks were observed among subjects who carry more risky genotypes.7.The A/C genotype of polymorphisms of DNA ligase I gene exon-6 lead unmarkable increased risk of lung cancer than wild genotype.8.Smoking is still the closest dangerous factor in development of lung cancer.In addition, passive smoking might associate with risk of lung cancer.Several kinds of indoor air pollution factors,which were rare in developed countries,such as the usage of solid fuel, non-usage of ventilation equipments and Chinese cooking style might be also associated to risk of lung cancer in Chinese population,especially Chinese women.