Parity-Induced Protection Against Breast Cancer
Annual rept. 1 Jul 1998-30 Jun 1999
PENNSYLVANIA UNIV PHILADELPHIA
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There is a strong correlation between a womans reproductive history and her risk of developing breast cancer. In particular, epidemiological studies have shown that women who undergo an early first-full term pregnancy FFTP are at a much reduced lifetime risk of developing breast cancer as compared to women who never have children. This reduced susceptibility to breast cancer following an early FFTP has also been demonstrated in both rat and mouse models. Although this observation is well documented, the underlying molecular mechanism for parity-induced protection is not known. One model to explain this effect would be that the relative distribution of epithelial cell subtypes dramatically change as a result of pregnancy, lactation and regression, and give rise to a population of epithelial cells with a reduced tumor susceptibility. In a second model, it is hypothesized that systemic changes in hormone levels, and the indirect result of these changes on epithelial cell subtypes, may impact the susceptibility to tumorigenesis in the parous breast. To distinguish between these models, we have initiated a project to isolate molecular markers demonstrating differential expression between nulliparous and parous rat mammary glands. Preliminary results suggest that this is a valuable approach in which to characterize the cellular and molecular changes that occur as a result of parity.
- Medicine and Medical Research