Hormones Induced by Pregnancy Inhibit Development of Breast Cancer

Paradoxically, pregnancy hormones are also able to stimulate cancer growth. Understanding this dichotomy was the goal of the current study undertaken by investigators at Albany Medical College (NY, USA). Their intent was to determine whether administered pregnancy hormones would elicit the cancer-inhibiting agent alpha-fetoprotein (AFP) from the liver, which would implicate AFP as a key modulator of hormonal anticancer activity. To this end they treated groups of nitrosomethylurea-exposed rats with saline, estrogen, progesterone, or human chorionic gonadotropin or allowed them to experience pregnancy. The animals were monitored for mammary cancer incidence and serum levels of AFP over time.

Results published in the November 24, 2009, online edition of the journal Cancer Prevention Research revealed that each hormone treatment reduced mammary cancer incidence and elevated serum AFP levels. AFP was shown to directly inhibit the growth of breast cancer cells growing in culture, suggesting that these hormones of pregnancy prevented breast cancer through their induction of AFP. This conclusion was strengthened by the finding that antibodies to AFP neutralized its growth-inhibiting effect.

"Hormones in pregnancy, such as estrogen, all induce AFP, which directly inhibits the growth of breast cancer,” said first author Dr. Herbert Jacobson, professor of reproductive sciences at Albany Medical College. "The body has a natural defense system against breast cancer. AFP needs to be safely harnessed and developed into a drug that can be used to protect women from breast cancer.”

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Albany Medical College