Study on the Relationship Between Breast Cancer and Female Endocrine Conditions , Hormone Therapy and Oral Contraceptive Usage among Women in Yazd , Iran During 2006-2007

Breast cancer is one of the most prevalent cancers among women and the prevalence of it in Yazd, Iran was reported as 2.62%. WHO mentioned postmenopausal hormone replacement and oral contraceptives as first group carcinogens. Endocrine conditions like late menopause, early menarche and nulliparity develop the risk of this cancer. This study was designed to determine the relationship between breast cancer and female endocrine conditions, hormone therapy and OCP usage among women in Yazd, Iran. In a case-control study which was done on 102 women with breast cancer and 200 healthy ones during 2006 2007.They were asked by a blinded interviewer about age of menarche, menopause, first full-term pregnancy, number of deliveries, history of Hormone therapy and OCP consuming. Cases selected randomly among women who was admitted in oncology department for breast cancer while controls matched with cases and did not have history of any chronic or malignant disease. Chi-square method with a confidence interval (CI) of 0.95 and two sample independent t-test was used. Results revealed that Mean± SD age was 48.61±10.63 for cases and 43.43±10.01 for controls. 44.4% of cases had regular monthly period while 26.3% had irregular. There was no significant difference between case and control groups for having monthly period. 61.1% of cases used contraceptives while 44.7% of healthy ones used it. Contraceptives usage was significantly different between two groups (P=0.009, CI=0.95). Mean± SD age of first full-term pregnancy for cases was 21.19±4.40 while in controls it was 32.75±3.25 which was significant in analysis (p=0.00, CI=0.95). There was also a significant difference between case and control groups for numbers of pregnancy (P= 0.009). It was concluded that in our society ovulatory cycles and hormone replacement therapy was not as risk factors, but using oral contraceptives recognized as a risk factor. Results also showed that younger age of first full term pregnancy and number of pregnancies were as risk factors for breast cancer in contrast with some other studies. Key word: Breast cancer Pregnancy Contraceptive Monthly period INTRODUCTION A short duration of menopausal hormone Breast cancer is one of the most prevalent was disappeared 5 years after cessation [3]. The recent cancers among women worldwide. Differences dramatic decline in MHT use in united states was related between high-incidence and low-incidence regions to decrease in the incidence of estrogen receptor positive showed that environmental factors are able to tumors confirming a relationship between MHT and some influence breast cancer risk [1]. The prevalence of kinds of breast cancer [4]. World Health Organization breast carcinoma among women in Yazd, Iran was (WHO) categorized postmenopausal hormone reported as 2.62% [2]. replacement and oral contraceptives as first group therapy(MHT) elevated the risk of breast cancer which Middle-East J. Sci. Res., 8 (1): 34-39, 2011 35 carcinogens [5]. Investigations have showed an increase RESULTS risk among women who used oral contraceptives, especially in ones that used them before a first full-term The number of cases and controls were 102 and 200, pregnancy [6-8]. Some studies showed that using respectively. All were females that their Mean±SD age progesterone and estrogen in combination increased was 48.61±10.63 for cases and 43.43±10.01 for control the risk of breast cancer more than estrogen alone group. [3, 9-14]. Endocrine conditions such as late menopause, 44.4% of cases had regular monthly period while early menarche and nulliparity develop the risk of breast 26.3% had irregular monthly period. In control group cancer [15-18]. women who born their first child before 24 regular and irregular monthly period was reported 55.3 and years old have less risk in their lifetime for developing 18.1%, respectively (Table 1). Chi-square test showed that breast cancer [16]. A meta-analysis on Asian women there was no significant difference between case and showed that more than three abortions, family history of control groups for having monthly period. breast cancer,age at first live birth more than 30 years old We divided them into 2 groups: having monthly and age at menarche less than 12 years old increased risk period (even irregular) and not having monthly period, of cancer in them [19]. Again there was no significant relationship between case This study was designed to determine the and control groups. relationship between breast cancer and female endocrine Mean± SD age of menopause for cases and controls conditions, hormone therapy and OCP usage among were 47.17±6.61 and 46.39±5.87. Independent Samples women in Yazd, Iran. t-test showed that there was no significant relationship MATERIALSAND METHODS (P=0.576,CI=0.95). Odds Ratio for age of menopause was In a case-control study which was done in 2006 to 61.1%of breast cancer women used contraceptives 2007, 102 women with breast cancer and 200 healthy ones while 44.7% of healthy ones used it. Results of Pearson were asked some questions about their age of menarche, Chi-square test confirmed that contraceptives were as a age of menopause, number of deliveries and age of first risk factor in our society. (p=0.009,CI=0.95). Cases had full-term pregnancy.They were also asked about history 1.942 times more risk than controls for developing breast of Hormone therapy and OCP consuming. Breast cancer cancer by contraceptive usage (Table 1). women selected randomly among women who lived in 28.6% of women who were in menopause age used Yazd since 10 years ago that had pathologic diagnosis for hormone replacement therapy in cases while it was 33.3% breast cancer and was admitted to Oncology Department in control group. Chi-square test stated that there was no in this city while control ones chose according to significant difference between cases and controls for characteristics of cases and matched with them. Control taking sex hormones after menopause. women did not have history of cardiovascular disease, Mean± SD age of first full-term pregnancy for diabetes mellitus and any other malignancies. case group was 21.19±4.40 while in control group it All data gathered by a questionnaire designed was 32.75±3.25. Independent t-test showed a according to the similar, previously published studies significant difference between cases and controls which its validity and reliability confirmed with pilot (p-value=0.00, CI=0.95). Age at first full-term pregnancy studies. Each questionnaire fulfilled by an interviewer could be a risk factor of breast cancer in this community. who asked the questions and explained about them. Younger first full-term pregnancy could increase the risk For more validity interviewer and analyzer were of breast cancer in this study. blinded and did not know about cases and controls. All data gathered and analyzed by descriptive and analytic tests by SPSS software. For signification evaluation we used Chi-square method with a confidence interval (CI) of 0.95. Also for parametric variables two sample independent t-test used to estimate the differences between case and control groups along with logistic regression for association of variables with breast cancer. between the age of menopause and breast cancer