A Population-based Case-control Study On The Risk Factors Of Colorectal Cancer In Cixi City

Backgrounds & ObjectivesColorectal cancer is one of the common digestive canal cancers and is detrimental to human's health.It is the second high incidence disease in the western countries,and is the fourth or fifth cause of death in china.Additionally;its incidence and mortality have increased year by year.It should be paid attention to the exceedingly increasing incidence of colorectal cancer in some areas especially in big cities.So is the city of Cixi in Zhejiang province which located on the south shore of Hangzhou Bay. According to surveillance information of cancers in Cixi residents,the mortality of colorecral cancer in Cixi is 8.23 per one million,which made it become the fourth cause of death from cancer.The mortality in Cixi is lower than that in western countries,but it is rising year by year.The study on the risk factors of colorect cancer has progressed in many areas during recent years,but it has never been carried out in Cixi.Therefore,the study on the risk factors of colorectal cancer is essential to find out available measures for controling and preventing the disease in Cixi city.To explore the risk factors of colorectal cancer in Cixi city,and provide scientific evidence for the disease control and prevention,which can restrain the rising tendency of colorectal cancer eventually,a case-control study was conducted. Materials & MethodsCases of the study were survival patients with colorectal cancer diagnoseded by country or super hospitals.Totally,there were 148 patients,who were all local residents in Cixi.12 patients of them refused to take part in or could not be found,so 136 patients were investigated finally.Controls of the study were cancer-free healthy persons who did not suffer with digestive system diseases,and 1:1 matched to cases by gender,age(±3 years old),and resident area individually.Specialized questionaires were adopted,which were filled in by trained investigators after interviewing objects.The content of investigation includeds demographic characteristics,diet habits,individual and family history of disease,psychological factors and so on.After questionaires were coded unitedly,data were input into computors by Epi-data software,then database was set up.Using Stata8.0 and SPSS13.0,each variable was analyzed with single factor conditional logistic regression,and the value of odds ratio (OR),95%confidence interval(95%CI)and P value were calculated.The OR value of the factors with significant statistic correlation were adjusted using multi-variable logistic regression model.Results1.Associations between dietary habits and colorectal cancerAll kinds of food were investigated in detail in this study.After analyzing the consumption of starches,meat,fish,shellfish,egg,bean products,dairy products,fruit, dry fruirt and condiment,six significant factors were found out as follows:crab(salted), inkfish,squid(fresh),mantis shrimp(fresh),clam(fresh)and jellyfish(raw).There were negatively related with colorectal cancer,ORs were 0.41,0.39,0.43,0.38 and 0.54(P＜0.05),respectively.Contrarily,eating fat meat was positively associated with colorectal cancer and OR was 1.94(95%CI:1.11～3.44). 2.Associations between lifestyle factors and colorectal cancerAfter analyzing running water(ground water source),running water(well water source) deep well water,rain water and pure water,we found that drinking running water was negatively related with colorectal cancer and the OR value of drinking running water for fifteen years and over was 0.09(95%CI:0.02～0.33).Smoking,drinking and tea drinking were not statistically significant,however,refrigeration usage and oil smoke exhauster usage were significantly associated with colorectaI cancer,the OR values were 0.40(95%CI:0.21～0.74)and 0.36(95%CI:0.20～0.68)respectively.3.Association of colorectal cancer with individual and family disease historyThere were no statistical significance compared with colorectal cancer and individual and family history of disease such as chronic proctocoliris,acute appendicitis,viral hepatitis,cholithiasis,chronic cholecystitis,diabetes and other cancers.4.Associations between psychological factors and colorectal cancerEleven factors including character,enjoying bustle,emotions,being prone to anger, being worried about family problems,mood,marriage,family condition,interpersonal relationships,psychological status and mental injury were analyzed.It was shown that three factors containing enjoying quiet,poor self-adjusting ability and mental depression were statistically positively related with colorectal cancer,and the OR values were 2.02,5.48 and 4.50,respectively.After the removing of some unimportant factors from twenty-eight factors(P≤0.10) through single factor conditional logistic regression,twenty-one factors including chronic proctocoliris,diabetes,brother or sister history of cancer,psychological status, mood,enjoying bustle,refrigerator usage,oil smoke exhauster usage,salt or salt-free taste,duration of drinking running water,consuming of salted meat,fat meat, crab(salted),inkfish,squid(fresh),mantis shrimp(fresh),clam(fresh),jellyfish(raw), razor clam(fresh),bullacta exarata(salted),fruit(apple,peach,plum,pear)and dry fruit(peanut,mealon seeds)were analyzed by multivariate factor conditional logistic regression.The results indicated that oil smoke exhauster usage,eating inkfish, squid(fresh)and dry fruit(peanut,mealon seeds)were negatively related with colorectal cancer,however;eating fat meat,chronic proctocoliris and poor self-adjusting ability were positively related with colorectal cancer.ConclusionsThe study indicates that eating fat meat,chronic proctocoliris and poor self-adjusting ability may increase the risk of colorectal cancer.On contrary,oil smoke exhauster usage,eating inkfish,squid(fresh)and dry fruit(peanut,mealon seeds)have protective effect on colorectal cancer.