| Popis: |
Epidemiological and clinical data have provided enough information for characterizing the profile of the woman at risk of developing sporadic breast cancer, which constitutes greater than 95% of all cancers diagnosed worldwide [1]. These data highlight the importance of events influenced by ovarian function in relation to age and parity history, such as the increased risk associated with early menarche, i.e. before age 12, nulliparity, late first full-term pregnancy, and late menopause [2 – 6]. Variations in this relationship among ovarian, age, and reproductive factors that result in protection are late menarche, early single or multiple parity [7], and early menopause [2 – 6]. Therefore, it can be concluded that these conditions represent the ideal goal to be achieved for protecting the population at large. Our work has been designed largely to clarify the ultimate mechanisms that mediate the protective effect of early pregnancy. Towards this purpose we have analyzed the development of the breast under the influence of endocrinological events occurring at various times during the lifespan of a woman [8 – 11]. These studies, in correlation with the pathogenesis of breast cancer [11 – 12], and comparative analyses of experimental in vivo and in vitro models [13 – 29], led us to conclude that the key element in the protection of the breast from cancer initiation was the differentiation of this organ induced by pregnancy “before” the mammary parenchyma was affected by a known or still unknown carcinogenic stimulus [30 – 33]. |
