Analysis Of Serum Levels Of 14 Trace Elements In Breast Cancer Patients

Background and objective:Breast cancer is the most common malignant disease in women,with its incidence having risen continuously,accompanied by lowered age of onset. Experimental and epidemiological studies suggest that serum levels of trace elements may be associated with breast cancer risk.The objective of the present study was to analyze serum levels of 14 trace elements,including Zn,Mn,Al,Cd,Fe,Mg,Ca,Pb, Cu,Ni,Ti,Co,Li and Cr,in breast cancer patients,and with a progress of the disease to investigate the associations between serum levels of trace elements and the risk of breast cancer.Materials and methods:MaterialsFifty-eight female patients,with histopathological diagnosis of breast cancer,aged 26-62 years,were selected from Provincial Hospital Affiliated to Shandong University, Jinan.Histopathological examination showed that 5,31,and 22 patients belonged to clinical stageⅠ,Ⅱ,andⅢrespectively.Fifty age-matched healthy women who attended routine physical examination in the same hospital were selected from the same region.All subjects gave consent for inclusion in the study.These subjects came from the population residing in and around Jinan and were representative of the population.A questionnaire was administered to obtain a comprehensive interview of lifestyle habits,medical history and use of medications.Factors that have been associated with breast cancer risk were available from the questionnaire:menopausal status,family history of breast cancer in the first-degree relatives,No.of full-term pregnancies,age at menarche,age at first live birth,age at menopause,alcohol consuming,oral contraception and hormonal replacement therapy.Body mass index was calculated as weight/height squared(kg/m~2).We selected controls who were matched to the patients for age and other known risk factors of breast cancer and excluded women with history of any tumor or breast disease.Both the patient and control group had no history of previous exposure to heavy metals as all subjects did not report any occupational/accidental exposure to heavy metals.A potential selection bias may have occurred if there were significant differences between the two groups in the known breast cancer risk factors above.Determination of ElementsBlood samples after a 12-hour overnight fasting were collected from an antecubital vein from all the subjects.Serum was obtained by centrifuging all subjects' blood samples and stored at -20℃until analyzed.A Spectraspan -V(Beckman) direct current plasma atomic emission spectrometer(DCP-AES) was used to determine the serum levels of Zn,Mn,Al,Cd,Fe,Mg,Ca,Pb,Cu,Ni,Ti,Co,Li and Cr according to the manufacturer's instructions.Serum samples of 0.5 ml each were diluted with deionized water in the proportion of 1:3.Quality controls were checked.A quality check sample was always run with each set of samples to maintain accuracy. Detection limits were 0.0174μg/ml for Zn,0.0041μg/ml for Mn,0.0072μg/ml for Al, 0.0048μg/ml for Cd,0.0106μg/ml for Fe,0.032μg/ml for Mg,0.016μg/ml for Ca, 0.0193μg/ml for Pb,0.0033μg/ml for Cu,0.0032μg/ml for Ni,0.0027μg/ml for Ti, 0.009μg/ml for Co,0.0029μg/ml for Li and 0.0046μg/ml for Cr.Statistical AnalysisStatistical analysis was carded out using SPSS 13.0.The characteristics of the patient and control groups were compared using the Student's t-test for continuous variables and chi-square test for discrete variables.The distribution of measurement data of trace elements was checked and showed normal distribution.The Student's t-test was used to compare the serum levels of the 14 trace elements between patient and control groups.The one-way ANOVA was used to compare the serum levels of the 14 trace elements among patients with different stages.The results are expressed as means±standard deviations.All P values were 2-sided,with P＜0.05 indicating statistical significance.Results:The characteristics of the patient and control groups:There were no significant differences between breast cancer patients and healthy controls with respect to age, body mass index,first-degree relative with breast cancer,menopausal status,late age at first full-term pregnancy(＞30 years),early menarche(＜12 years),late menopause (＞55 years),No.of full-term pregnancies,oral contraceptive use,use of hormone replacement therapy and alcohol consumption.Comparison of serum levels of the 14 trace elements between the patients with breast cancer and the normal controls:The two groups had significant differences in serum levels of Mn,Al,Cd,Fe,Mg,Cu,Ti,Co,and Li,while had no significant differences in serum levels of Zn,Ca,Pb,Ni,and Cr.Compared to the normal controls,the patients with breast cancer had significantly higher serum levels of Cd, Mg,Cu,Co,and Li,and marginally significantly higher serum Cr levels,while significantly lower serum levels of Mn,Al,Fe,and Ti.Comparison of serum levels of the 14 trace elements among the patients with stageⅠ,stageⅡand stageⅢbreast cancer:There were no significant differences in the serum levels of all the 14 trace elements amongst the three groups.Conclusions:There may be associations between the changed serum levels of trace elements and breast cancer risk.Changes of serum levels of trace elements may be of potential to have diagnostic and preventive value for breast cancer,although it warrants further investigations on larger sample size and on more other trace elements of interest,and prospective studies which will use serum level of trace elements of a normal population before breast cancer diagnosis and follow up the breast cancer incidence of the population.