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Predicting Individual Breast Cancer Risk May Be Possible
An international team of researchers led by the Harvard Stem Cell Institute have discovered why women who give birth in their early 20s are less likely to develop breast cancer than women who don’t, triggering a search for a way to confer this protective state on all women.
The researchers are now testing p27, a mammary-gland progenitor (MGP) marker, on tissue samples collected from thousands of women over decades — women whose medical histories have been closely followed — to see whether it is an accurate breast cancer predictor in a large population. If the hypothesis is confirmed, which appears likely within a few months, the commercial development of a clinical test for breast cancer risk would follow.
In a paper published in Cell: Stem Cell, the researchers describe how a full-term pregnancy when a woman is in her early 20s reduces the relative number and proliferative capacity of MGPs — cells that have the ability to divide into milk-producing cells — making them less likely to acquire mutations that lead to cancer.
By comparing numerous breast-tissue samples, the scientists found that women at high risk for breast cancer, such as those who inherit a mutated BRCA1 or BRCA2 gene, have higher-than-average numbers of MGPs. In general, women who carried a child to full term had the lowest populations of MGPs, even when compared with cancer-free women who had never been pregnant. In addition, in women who gave birth relatively early but later developed breast cancer, the number of MGPs was again observed to be higher than average.
“The reason we are excited about this research is that we can use a progenitor cell census to determine who’s at particularly high risk for breast cancer,” said study leader Dr. Kornelia Polyak. “We could use this strategy to decrease cancer risk because we know what regulates the proliferation of these cells, and we could deplete them from the breast.”
Source: Harvard University; August 12, 2013.