| ObjectiveTo analyze the association between smoking and secondhand smoking(SHS)at family and death of colorectal cancer.Materials and MethodsData selected from nationwide retrospective survey of smoking and mortality in 1986-1988,including the personal information and smoking history of deceased,as well as smoking history of spouse.Colorectal cancer death and surviving spouse in 30-79 years old were selected as the subjects.Study of SHS at family focused on female,becasuse in China smokers are overwhelming male,and in this study the smoking prevalence of surviving spouses of nonsmoking female coloretacl cancer(53.56%in urban areas,66.84%in rural area)was much higher than in male(9.18%in urban areas,5.54%in rural areas).Study design:(1)Ecological study:In order to ensure the effectiveness of statistics,23 cities in female were selected to calculate the correlation coefficient of family smoking and colorectal cancer death.(2)Case control study:1.Relation on Smoking and death of colorectal cancer:Cases were the colorectal cancer deaths.Controls were selected from surviving spouses based on 1:2 ratios according to the gender,age(±5 years)and region.2.Relation on family SHS and death of colorectal cancer:Taking nonsmoking female colorectal cancer death as cases and nonsmoking surviving spouses were selected as the control group on above conditions.Statistical analysis:Correlation coefficient was calculated by Spearman’s rank correlation.Unconditional logistic regression model was used to evaluate the odds ratio(OR)and 95%confidence intervals(95%CI)for case control study.Results(1)Ecological study:Study of 2684 colorectal cancer deaths in 23 cities was found that husband who was smoking duration in years>40 significantly positive correlated with the mortality of female colorectal cancer,r=0.48,P=0.02.As hierarchical analysis showed,the mortality was significantly positive correlated with husband smoking≥20 pack-years in 30～39 age group,r=0.44,P=0.02.In 50～59 age group,it was positively related to husband smoking per day 10～19 and smoking duration in years<30,r=0.552、0.551,P<0.05.In 70～79 age group,they in age of starting smoking<20,smoking duration years<30,smoking<10 pack years were 0.51,0.46,0.59,respectively,P<0.05.(2)Case control study:1.Relation of smoking and colorectal cancer:Male:Cases of urban were 3971,and controls were 7942.In rural,they were 1157 and 2314,respectively.After adjusted age,smoking significantly correlated with colorectal cancer in urban,OR=1.136(95%CI:1.051-1.228).In rural,it was 1.445(95%CI:1.236-1.689).In urban,risk of colorectal cancer death were 1.217(95%CI:1.103-1.343)、1.114(95%CI:1.009-1.231)、1.197(95%CI:1.088-1.317)in daily smoking≥20,smoking duration ≥40 years,smoking ≥20 pack-years,respectively.In rural,they were higher,1.662(95%CI:1.366-2.022)、1.510(95%CI:1.247-1.829)、1.478(95%CI:1.209-1.808).Female:Cases in urban were 2798,and controls were 5596.In rural,they were 685 and 1370.After adjusted age,OR in urban was 1.020(95%CI:0.896-1.161),and rural was 1.106(95%CI:0.801-1.526).Risk in city female cigarette smoking≥40 years was 1.306(95%CI:1.022-1.669),but in rural did not found smoking index and colorectal cancer death had significant correlation.2.SHS at family and death risk of colorectal cancer in nonsmoking:Urban Areas:Cases were 2160.Controls were 4320.After adjusted age,compared with no exposure to SHS at family,risk was 0.677(95%CI:0.610-0.752)in urban non-smoking female.OR is 0.876(95%CI:0.696-1.103)、0.598(95%CI:0.518-0.690)、0.638(95%CI:0.560-0.727),respectively,whose husband had smoked<20 years,≥40 years,and ≥20 pack-years.Rural Areas:Cases were 567 and controls were 1134.After adjusted age,female colorectal cancer death risk in husband smoking was 0.831(95%CI:0.668-1.035).Smoking index of husband had no significant correlation with colorectal cancer death of women.ConclusionsMale smoking significantly increased the death risk of colorectal cancer.In urban female,cigarette smoking over 40 years the risk increased.Ecological study found husband smoking significantly increased risk of colorectal cancer deaths among women,while Case control Study found that no significant correlation between them.In urban it was a protective factor,this may be due to the unadjusted other risk factors of colorectal cancer. |
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