A Case-control Study On The Relationship Between Organochlorine And Breast Cancer

A BackgroundBreast cancer is one kind of the most common malignant cancers that jeopardize women's health.Datas and materials from the World Health Organization(WHO)have showed that every year in the world there are more than 1,200,000 new cases occur and will cause 517,000 women death.It is estimated that the incidence of breast cancer in north America and northern part of Europe is approximately 4-fold higher compared with the incidence in Asia,Africa and Latin America.China is the country with a relatively low incidence rate,but recently the rate has increased by 3%to 5%annually and the age of onset has inclined to be younger.This condition is especially distinctive in Shanghai,Beijing,Tianjing and China's coastal area.Etiological study reveals that breast cancer is related with multiple factors including genetic/family factor,genesis/hormone factor,life style/behavior factor and environmental factor.Most epidemiological studies have reported that no more than 50%of breast cancer could be explained by the known factors such as gender,older age, early age in menarche,late age in menopause,older age when primiparity and breast cancer history of first degree relatives.Therefore,more and more focuses are concentrated to environmental factors and researchers hope it will help to illustrate the etiology of breast cancer.Lacteal gland is a target organ of many kinds of hormones such as estrogen, progestin,prolactin et al.Nowadays researchers believe the mechanism of breast cancer is mainly related with estrogen metabolism.Environmental hormone-like active compound will enhance the carcinogenesis of breast cancer through mimicing estrogenic effect or disturbing estrogen metabolism pathway.Other risk factors of the breast cancer share the same mechanism mentioned above.Researchers have reported environmental contaminates such as PCBs and OCPs will probably increase the risk of estrogen metabolism related disease.In the year 2001, these pollutants are registered in the"Stockholm Convention on Persistent Organic Pollutants"by UNEP.Investigations have discovered that long-term exposure to low concentration of environmental organochlorines will increase the incidence of breast cancer,especially in premenopausal women.But there are also researches that found no relationship between breast cancer and organochlorines.In our nation,most researchers pay attention to the monitoring of PCBs and OCPs residual.Materials from population-based studies are still in the shortage,therefore it is worth conducting systematically epidemiological studies to bring new ideas and evidences.B ObjectivesWe will combine both datas from lab and investigation to give a primary assessment of organochlorine exposure-level and the relevant influential factors. Therefore,we can probe and explore the relationship between breast cancer and organochlorines.Moreover,we can offer methods and evidences to the control and prevention of breast cancer and illuminate the etiological factor and mechanism to a further and deeper step. C MethodsOur research is a population-based case-control study.The subjects are all from Jiashan county,Zhejiang province.We have collected a total number of 78 primary female breast cancer cases which are newly-happened and patho-definited.We have got 72 Controls matching with age,investigate time and residence.All the subjects have been informed with the specific purpose of our research and all of them have signed informed consent.Consequently,we have collected datas in general state of health,eating habit,life style,patient history,genesis and endocrine secretion and we have got the blood preparation.As a result,150 portions of plasma are extracted from the blood sample by liquid-phase microextraction.The contents of organochlorines such as PCBs,HCH and DDT are detected and analyzed by gas chromatograpy -elctron capture detector.Statistical analysis is carried out between cases and control groups.D Results(1)Detection rate of PCBs among cases and controls ranges from 96.2%to 100% and 91.7%tol00%respectively.Both the detection rate of HCH and DDT are 100%. The median contents of PCBs,HCH and DDT among cases are 1.3974ng/ml, 0.6514ng/ml and 0.9544ng/ml respectively,while those among controls are 0.7883ng/ml,0.5569ng/ml,0.5959ng/ml respectively.By the Kolmogorov-Smirnov test of normality,the results showed significantly skewed distribution(p＜0.001).Therefore,the differences of 13-kinds organochlorine pollutants between case and control were compared by rank sum test.The plasma content of PCB101,PCB118,PCB138,PCB153,PCB180,total PCBs,p-HCH, p,p'-DDE,total DDT,total HCH and p,p'-DDT among cases are higher than that in controls,the difference has statistical significance.(2)We have divided all the subjects into two levels.The upper quartile of the control group is considered as reference level,the rest belong to exposure level.After adjusting age,BMI,occupation and education factors,logistic regression shows some kind of organchlorines have positive relationship with breast cancer.Reference for both literature report and expertise,several factors are choosen as consideration variables,which was the exposure levels of organic chlorine,age, breastfeeding history,and benign breast history.Statistical Analysis of all variables by multi-factor logtistic regression,in theα-0.10 level,through the stepwise regression, and ultimately able to enter the multi-factor model of breast cancer,were only eight indicators of organochlorine pollutants.Descending order of OR value,it was from PCB138,total PCBs,PCB153,β-HCH,PCB118,P,P'-DDE,PCB180,to total HCH.Comprehensive our research and documentation of the results,suggesting that PCB138,PCB153,andβ-HCH,p,p'-DDE can be used as an indicator to evaluat effects of PCBs and OCPs exposed.E ConclusionWe conclude from the result of the population-based case-control study as followed.(1)Detection rates of PCB and OCPs indexes among all the subjects were higher, respectively.Their contents of plasma among cases were higher than that in controls, the difference has statistical significance.(2)Organochlorine exposure may have possible positive relationship with breast cancer.In our research,we find a positive relationship between breast cancer and PCB138,PCB153,PCB118,PCB180,total PCBs,(3-HCH,p,p'-DDE and total HCH.(3)Literature report have revealed that PCB138 and PCB153 can be used a index for PCBs exposure assessment while P-HCH and p,p'-DDE can be for OCPs.