Purpose: To assess the influence of reproductive factors in the occurrence of breast cancer in women, taking into account the presence/absence of genetic predisposing mutations.
Methods: 100 patients with breast cancer were included. The genetic testing was conducted through a multigene panel. Reproductive characteristics were noted for all patients: age of menarche, age of the patient at first full term pregnancy, number of pregnancies, number of full-term pregnancies, breastfeeding interval, number of abortions, and menopausal status at the time of diagnosis. The patients were divided into three groups according to their mutations: BRCA1, positive for mutations other than BRCA1 and negative.
Results: The risk of breast cancer was not influenced by the number of abortions, parity, age at first pregnancy, age at menarche and menopausal status, or by oral contraceptive use in carriers of pathogenic mutations group in the BRCA1 group. The present study has demonstrated the protective effect of breastfeeding only in patients without genetic risk (p=0.0344). In contrast, breastfeeding did not influence breast cancer occurrence in BRCA1 mutation carriers' group (p=0.2321).
Conclusions: Breastfeeding represents a protective mechanism only in patients without genetic breast cancer predisposing mutations. Environmental and reproductive factors can impact the risk and the age of onset of breast cancer in patients carrying pathogenic mutations, but the mechanisms of action are not fully understood.