MU researcher links hormone replacement therapy to bre...(rs. The synthetic progestin Hyders t...)

The synthetic progestin Hyders team studied is known as medroxyprogesterone acetate (MPA), which is commonly used in HRT. Using an animal model, Hyder introduced MPA to the animals that were carrying human breast cancer cells. When the breast cancer cells were exposed to MPA, they began growing at an accelerated rate. Later, when the research team exposed the cells to the antibody known as 2C3, or PRIMA both of which block formation of new blood vessels in tumors the tumor cells failed to grow and spread in response to the MPA.

Since MPA is a synthetic hormone, it stays in the body longer, Hyder said. Unfortunately, while the drug is used to protect the uterus from the harmful effects of estrogens in HRT formulations, it is hurting the breast.

The Womens Health Initiative estimated a 26 percent jump in the number of breast cancer cases among women ingesting estrogen and progestin. Hyder believes that a large number of these women might also have a p53 protein that is not active and, therefore, not able to inhibit MPA-induced growth factor that helps to proliferate the tumor cells. Hyder cautioned that these studies are at an early stage and a lot of work remains to link progestin use firmly with progression of breast cancers in women.

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