Reproductive factors and risk of breast cancer

Abstract

Background: Breast cancer is the most common type of female cancer among Iraqi women. Some reproductive factors have been shown to be associated with an increase in breast cancer risk. There haven’t been any studies investigating the association between pregnancy outcome and breast cancer in Iraq. Objectives: The aim of this study was to examine the possible associations between some reproductive factors as age of menarche, age at first delivery, parity and pregnancy outcome (i.e normal full term birth, abortion, premature delivery or multiple births) and risk of maternal breast cancer in AL-Anbar Governorate, west of Iraq. Patients and methods: The study was conducted in the oncology clinic in AL-Ramadi General Hospital during the period from October 2011 to April 2012. The study consisted of 100 breast cancer cases confirmed on histopathology and 200 group- matched healthy controls. Bivariate analyses included odds ratio (OR); and 95% confidence interval (CI) for odds ratio were also performed. Results: results showed that earlier age at menarche <12 years, older age at first full term birth>30 years, and not having given birth were significantly associated with increased risk of breast cancer. With regards to birth outcome, full term birth was found to be associated with lower risk, the more the number of full term births, the more protection was found.Premature deliveries < 8 months of gestation was found to be significantly associated with nearly three times risk compared to those with full term deliveries (O.R.=2.98, CI=1.60-5.56, p= 0.002), while premature deliveries > 8 months was not associated with risk, so as the effects of stillbirth. History of more than one abortion was found to slightly increase the breast cancer risk (O.R=1.24,CI= 0.70-2.18, p= 0.57). Having twin or multiple births were found to be protective against breast cancer (O.R=0.32, CI=0.12-0.86, p=0.019).Conclusion: Risky reproductive factors for breast cancer included early age of menarche, late age at first full term birth, and nulliparity. More than one abortion seemed to slightly increase the risk, while on the other hand premature deliveries < 8 months significantly increased the risk of breast cancer. Pregnancy outcome in a form of full term birth, multiparty and twin births were protective against breast cancer