Comparative Study of Human and Rat Mammary Tumorigenesis

We have learned through the study of human breast cancer that this disease is the result of a combination of factors, among them external factors such as ionizing radiation, diet, socioeconomic status and endocrinologic, familial or genetic factors. Among all of these factors, the development of breast cancer is influenced by the reproductive history of the individual; lower risk of breast cancer has been reported in women that have had an early full-term pregnancy (109, 110, 154, 162).