How HRT is linked to breast cancer

COLUMBIA, Mo. (UPI) — Hormone replacement therapy, or HRT, may play a role in promoting cancer tumor cell proliferation, U.S. researchers suggest.

The study, published in Cancer Research, found tumor cells exposed to progestin — a hormone used in HRT — was linked to an increase in growth factor promoting new blood vessels in tumors.

The researchers also found using an antibody that prevents new blood vessel formation in tumors — known as PRIMA — re-activated the protein p53. When p53 was activated within tumor cells, the number of breast cancer cells reduced significantly.

“As women age, many develop tiny lesions in their breasts,” study leader Salman Hyder of the University of Missouri-Columbia said in a statement. “The majority of the time, these lesions never expand. We think this might be due to p53s. We found in our study that when the protein is active, it reduces the number of breast cancer cells in the body by inhibiting the growth factor that supplies blood vessels to the tumor.”

However, when the cells of these lesions are exposed to progestin in a body that does not have an active p53 protein, the researchers found that the cells might start expanding and turn into tumors, Hyder said.

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Copyright 2008 by United Press International

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