Pregnancy, p53 and breast cancer risk

BETHESDA — Early pregnancy is known to protect women from breast cancer, but the mechanism by which this is achieved remains unclear. In 23 October Proceedings of the National Academy of Sciences, Lakshmi Sivaraman and colleagues at the Baylor College of Medicine (BCM), Houston, Texas, challenge one leading theory and propose new ideas to explain their unexpected finding that the tumor suppressor gene, p53, seems to have a significant role to play.

"Before we started this study, we had no idea this [effect] would turn out to be related to p53," said Bert O'Malley, Chairman of the Michael DeBakey Center at BCM and the senior author on the paper.

The puzzle O'Malley and others in the field are trying to solve is why women who have a full-term pregnancy by age 19 have a 50% reduction in their lifetime breast cancer risk. A first pregnancy in the mid-20s appears to ...