RESUMO
Background: Recent studies suggest that the age at first pregnancy, number of children and the lapse between births may protect against breast cancer. Furthermore, serum levels of estrogen, prolactin and progesterone appear to contribute to the development of this tumors in obese women. Aim: To verify whether the variables age at first pregnancy, number of children, birth interval, hormone levels and nutritional status are associated with the age at diagnosis of breast cancer. Material and Methods: Retrospective analysis of medical records of550female patients, diagnosed and treated for breast cancer at a hospital in Spain between 2009 and 2012. Results: We found a significant and positive association between age at diagnosis of cancer and the variables age at first pregnancy, parity and interval between pregnancies. There was also a significant correlation (p < 0.000) between serum levels of estrogen, prolactin and progesterone and nutritional status of patients. Conclusions: In this sample, age at first pregnancy or number of children, hormone levels and nutritional status are related to the age of onset of cancer.