Neonatal Birth Weight of the Woman as a Risk Factor for Breast Cancer in her Life: a Case-Control Bicentric Study

BACKGROUND: It is a global fact that the birth weight is increasing during the years around the world and for this reason it is very important to be examined as a potential risk factor for breast cancer. According to data from World Health Organization, breast cancer is the second most frequent malignancy across the world, after lung cancer, in Europe including Greece in incidence and mortality for women between the ages 0-85 years old. OBJECTIVE: The aim of this study was to investigate a possible association between neonatal birth weight of the women and breast cancer risk in Greek women. Although that many studies concluded that birth weight is positively related with breast cancer reinforcing the theory that breast cancer may originate in utero, some studies found no association. Moreover, the results from previous studies are inconsistent maybe due to several factors such as the study design and the number of cases. METHODS: This study was a case-control retrospective bicentric study. The case group included 238 women with breast cancer, while the control group included 153 women without breast cancer who consulted in two breast clinics in Greece. In all women, a clinical examination and breast ultrasound were achieved. Moreover, digital bilateral mammography was performed in patients older than 40 years. RESULTS: According to Fisher’s exact analysis, there is a statistically significant relationship between the higher women’s neonatal birth weight and the risk for breast cancer (p<0.001). More specifically in the group of women with breast cancer, 61% of them had more than 3500 grams birth weight, in contrast with 7.8 % in the control group. In our cohort, women who had birth weight more than 3500 grams are more likely to develop breast cancer in their life. CONCLUSION: Our study trend to show that the increased neonatal birth weight may influence future risk of breast cancer. However, further studies with larger number of participants are needed in order to clarify the role of birth weight as a complementary risk factor of breast cancer.