Serum Lipids And The Risk Of Female Breast Cancer:A Prospective Cohort Study

BackgroundBreast cancer is the most common malignancy in women worldwide.According to the GLOB OCAN 2020 database released by the International Center for Research on Cancer,female breast cancer surpassed lung cancer for the first time to become the most common cancer.In 2020,there were about 2.26 million new cases of breast cancer worldwide,accounting for 11.7%of the total incidence of cancer.About 680,000 women died of breast cancer,which is the leading cause of female cancer death.China’s cancer statistics report shows that in recent years,the incidence and mortality of breast cancer have been on the rise,posing a serious threat to the health of Chinese women.Although the treatment of breast cancer is becoming more and more perfect,finding the risk factors of breast cancer is of great significance for the prevention of breast cancer and reducing the burden of breast cancer in our country.With the change of lifestyle and dietary structure,the rate of obesity and patients with hyperlipidemia gradually increase,and the relationship between metabolic diseases such as lipid metabolism and malignant tumors has gradually become a hot topic of research.Lipids are essential substances in human cells and essential substances in the basic metabolism of cells.Dyslipidemia mainly refers to total cholesterol(TC),triglycerides(TG)and low-density lipoprotein cholesterol(LDL-C)increased and high-density lipoprotein cholesterol(HDL-C)decreased.In recent years,with the development of China’s economy and the change of dietary habits,the prevalence of dyslipidemia has increased,which has become one of the important public health problems,seriously affecting people’s health level.Epidemiological studies have shown that the major components of metabolic syndrome,including obesity,hyperglycemia,hyperinsulinemia,dyslipidemia and hypertension,can affect the occurrence and prognosis of breast cancer through various mechanisms.Among them,there are few domestic and foreign reports on the relationship between female breast cancer and blood lipid,and the results are inconsistent,and there is still a lack of large prospective cohort studies on the relationship between blood lipid indexes and breast cancer risk in China.Therefore,it is necessary to prospectively study the association between blood lipids and the risk of breast cancer in women from multiple dimensions by selecting single and complex lipid indexes.ObjectiveBased on the baseline data and follow-up data of the core cohort in Taizhou cohort,Jiangsu Province,this study investigated the association between single and complex lipid indexes and the risk of breast cancer,and explored the effects of menopausal status,cumulative years of menstruation and menopause age on the association between lipid indexes and the risk of breast cancer in women.In order to provide a theoretical basis for the identification of high-risk groups of breast cancer and the formulation of prevention strategies.MethodsA prospective cohort study was conducted,and the female population dynamically included in the core cohort of Taizhou Cohort from 2009 to 2016 was selected as the research object.The investigators interviewed and collected the basic demographic characteristics and physical indicators of the subjects face-to-face and sent blood samples for blood biochemical indicators detection.The main indicators of detection include TC,TG,LDL-C and HDL-C,fasting blood glucose,etc.Compound lipid indexes were calculated from conventional indexes,including TC/HDL-C,TG/HDL-C,LDL-C/HDL-C,Non-HDL-C(non-high-density lipoprotein cholesterol)and residual cholesterol,etc.Non-HDL-C is obtained from TC minus HDL-C.The remaining cholesterol is obtained by subtracting HDL-C from TC and then subtracting LDL-C.Breast cancer incidence and death outcomes in the cohort were collected and examined using a combination of active follow-up(face-to-face periodic follow-up in rural areas)and passive follow-up(annual visits to the tumor registry,health insurance system,and death reporting system).The first questionnaire was used as the starting point of follow-up,and the end point of follow-up was new breast cancer,death or the end of follow-up(December 31,2021).For dyslipidemia,refer to the clinical classification criteria of hypercholesterolemia(TC≥5.18mmol/L)in Chinese Adult Guidelines for the Prevention and Treatment of Dyslipidemia(2016 Revision).Hypertriglyceridemia(TG≥1.70mmol/L);Hyper LDL-C(LDLC≥3.37mmol/L);Hyper HDL-C(HDL-C≤1.04mmol/L).Any one of these criteria is considered dyslipidemia.Statistical software Stata16.0 was used for data collation and analysis.Bilateral P<0.05 was considered statistically significant.Stratified analysis was conducted according to menopause status,cumulative years of menopause and menopause age.Trend chi-square test was used to investigate the trend of changes in the incidence of breast cancer with blood lipid level.Multivariate Cox proportional risk regression model was used to calculate the hazard ratio(HR)and 95%confidence interval(CI)between different blood lipid indexes and the incidence of breast cancer.Results(1)29075 subjects were followed up for a total of 267092.30 person-years,with an average follow-up time of 9.19 years.During this period,276 new cases of breast cancer occurred,with an incidence density of 103/100000.According to the inclusion criteria,a total of 21261 subjects were finally included in this study.The comparison of baseline characteristics showed that there were statistically significant differences in the distribution of age,education level,age of menarche,age of menopause,menopause status and body mass index(BMI)between the breast cancer group and non-breast cancer group(P<0.05).In terms of lipid indexes,no significant difference was found between non-breast cancer group and breast cancer group(P>0.05).(2)Multivariate Cox proportional hazard regression model showed that elevated TC,TG,Non-HDL-C and residual cholesterol in the general population were risk factors for breast cancer.The risk of breast cancer was increased by 1.15(HR=1.15,95%CI:1.07-1.24)times,1.08(HR=1.08,95%CI:1.02-1.15)times and 1.22(HR=1.22,95%CI:1.12-1.33)and 1.23(HR=1.23,95%CI:1.12-1.35)times for every 1 unit increase in serum TC,TG,Non-HDL-C and residual cholesterol levels,respectively.The results of postmenopausal women were consistent with the general population.Only residual cholesterol had a statistically significant association among non-menopausal women.The results of stratified analysis according to the cumulative years of menopause have not changed.(3)Abnormal TC and TG were risk factors for breast cancer in the general population,and their HR(95%CI)were 1.69(95%CI:1.23-2.33)and 1.52(95%CI:1.08-2.14),respectively.Results were consistent between the postmenopausal women and the general population.There was no statistical association between dyslipidemia and breast cancer in non-menopausal women(P>0.05).(4)Trend Chi-square test results showed that the incidence of breast cancer in the general population and menopausal women showed an increasing trend with the increase of TC level(Ptrend<0.05).The results of multivariate analysis showed that the risk of breast cancer in the total population showed a gradual upward trend(Ptrend<0.05)with the increase of TC and TG concentrations,and reached the maximum when the concentration was at the highest quartile group,and the HR(95%CI)was 2.53(95%CI:1.57-4.10)and 1.64(95%CI:1.07-2.53).The results of postmenopausal women were consistent with those of the general population.(5)The analysis results of lipid complex index showed that the incidence of breast cancer in the general population,menopausal women and non-menopausal women showed an increasing trend with the increase of residual cholesterol level(Ptrend<0.05).In the total population,with the increase of Non-HDL-C and residual cholesterol levels,the risk of breast cancer showed a gradual upward trend(Ptrend<0.05).When the concentration reached the highest quartile group,the risk of breast cancer in the highest quartile group was 1.92 times(HR=1.92,95%CI:1.17-3.14)and 2.04 times(HR=2.04,95%CI:1.29-3.22)that in lowest quartile group.Results in postmenopausal women were consistent with those in the general population,while non-postmenopausal women had a statistically significant association only in the residual cholesterol group.ConclusionsAbnormal TC or TG in the general population are risk factors for breast cancer.With the increase of TC,TG,Non-HDL-C and residual cholesterol levels,the risk of breast cancer showed a gradual upward trend.The results of postmenopausal women were consistent with those of the general population.Therefore,maintaining appropriate lipid levels is of great public health significance for the prevention of breast cancer.Menopausal women should regularly detect lipid indexes,especially the levels of TC、TG、Non-HDL-C and residual cholesterol.In addition,the occurrence of dyslipidemia can be reduced by improving dietary habits or applying lipid-lowering drugs to reduce the risk of breast cancer.