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Pregnancy at early age protects against breast cancer

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     A full-term pregnancy at an early age protects against breast cancer. This is the finding of a new research from Fox Chase Cancer Center in Philadelphia. The research was headed research pathologist Irma H. Russo, M.D. This is not a new information since many studies around the world have established that a full-term pregnancy by age 20 reduces breast cancer risk by half. Studies by Russo and colleagues suggest that breast cells reach full maturity or full differentiation, only after a full-term pregnancy. Once this process is complete, the cells are less vulnerable to cancer-causing changes. Early pregnancy confers a strongest protective effect by limiting the time breast cells remain immature and making them mature differentiated cells.

    "A high-susceptibility or high-risk window exists early in life, between the start of ovarian function and the first pregnancy," explained Russo. "During this period, the mammary gland has continuously varying characteristics influenced by ovarian and pituitary hormones. These traits change during pregnancy under the influence of embryonic and placental hormones."

    Russo's laboratory has clearly shown that pregnancy and human chorionic gonadotropin (hCG), which is a hormone produced during pregnancy, are capable of inhibiting breast cancer in rats. The placental hormone hCG promotes full maturation of breast cells and also prevents development of cancerous changes in these cells later.

    "This led us to postulate that this hormone might be useful for breast cancer prevention in women," Russo said. "Toward this goal, we designed experiments to learn, first, whether the protection conferred by hCG results from genetic changes specific to this hormone and, second, whether a similar genomic signature would result from either pregnancy or ovarian steroid hormones." This study was presented recently at the Annual Meeting of the American Association for Cancer Research. The study used virgin rats treated with a daily hCG injection compared to untreated virgin rats.