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Authors: ADIGUN, M. O.
Keywords: Breast Cancer
Cardiovascular risk
Pre-menopausal lipoproteins
Issue Date: May-2013
Abstract: Oophorectomy is a management modality for Pre-Menopausal women with Breast Cancer (PMBC) resulting in reduced oestrogen levels and artificial menopause. Metabolic alterations occur during natural menopause while reduced levels of oestrogen (a known cardioprotective factor) may alter plasma lipids, lipoproteins and other cardiovascular risk factors. The effects of low estrogen levels, which occur in oophorectomised women are not known. This study was therefore designed to investigate the effects of oophorectomy on cardiovascular risk factors. In this longitudinal study, 69 women were recruited from the University College Hospital, Ibadan and environs. They consisted of 25 PMBC age-matched with 25 Pre-Menopausal women without Breast Cancer-Control (PreMC) and 19 Post Menopausal women without Breast Cancer as control for oophorectomised women (PostMC). Demographic (age, ethnicity, occupation and educational status), reproductive history (parity, age at menarche and menopause, age at first live birth, stage and duration of disease), Body Mass Index (BMI) and blood pressure (systolic-SBP and diastolic-DBP) were obtained from all groups by standard methods. Blood (10 mL) was collected at the luteal phase from PreMC, PostMC, PMBC before oophorectomy and 1, 3 and 6 months after oophorectomy. Plasma obtained was used for analyses of total Cholesterol (TC), High Density Lipoprotein Cholesterol (HDLC) and triglycerides levels by spectrophotometric methods. Low Density Lipoprotein Cholesterol (LDLC) and Very Low Density Lipoprotein Cholesterol (VLDLC) concentrations were computed using Friedwald’s formulae while estradiol level was assayed by EIA. Ratios of HDLC to TC, LDLC to HDLC and triglyceride to HDLC (indicative of low density lipoprotein particle size) were also evaluated. Data were analysed using ANOVA, Student’s t test and Pearson correlation coefficient and differences significant at p=0.05. Significantly lower triglycerides (134.810.0mg/dL, 171.223.0mg/dL), VLDLC (27.02.9mg/dL, 34.21.9mg/dL) levels and triglyceride to HDLC ratio (5.90.8, 15.04.3) but higher estradiol (261.019.0pg/mL, 102.1229.3pg/ml), DBP (78.82.1mmHg, 70.12.5mmHg) and SBP (1233.8mmHg, 112.43.2mmHg) levels were observed in PMBC before oophorectomy compared with PreMC respectively. PostMC had significantly higher SBP (125.34.9mmHg, 112.43.2mmHg) and TC levels (165.413.1mg/dL, 127.211.4mg/dl) than PreMC respectively. The BMI (kg/m2) of PMBC, PreMC and PostMC were similar (25.0, 25.2 and 26.0 respectively). The PMBC at 3 months had increased levels of triglycerides (182.021.0mg/dL, 135.010.8mg/dL), VLDLC (36.51.4mg/dL, 27.02.0mg/dL) and TC (185.517.6mg/dL, 135.29.8mg/dL) compared with PMBC before oophorectomy respectively. When PMBC at 3 months was compared with PostMC, the HDLC (36.04.1mg/dL, 25.02.7 mg/dL) and estradiol (158.331.5pg/mL, 55.310.6pg/mL) levels were significantly higher. The HDLC level was also higher in PMBC at 6 months compared to PostMC (47.18.8mg/dL, 25.02.7mg/dL). The plasma estradiol level of PMBC before oophorectomy reduced from 261.069pg/mL to 7723.4pg/mL at 1 month, increased to 158.0  31.5pg/mL at 3 months but reduced to 89.025pg/mL at 6 months. Elevated levels of high density lipoprotein and estradiol were found in oophorectomised women with breast cancer. Increased estrogen from one month to six months after oophorectomy could be due to extraglandular estrogen production. The safe effects of oophorectomy on lipids and lipoproteins in premenopausal Nigerian women with breast cancer suggest low cardiovascular risk.
Description: A Thesis in the Department of Chemical Pathology Submitted to the Faculty of Basic Medical Sciences In partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY of the UNIVERSITY OF IBADAN
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