Short-term estrogen may offer protection.

2002 NOV 14 - (NewsRx.com & NewsRx.net) -- Short-term use of pregnancy-level estrogen, designed to mimic pregnancy, is highly effective in protecting women from breast cancer, according to a study presented at the American Association for Cancer Research's first annual Frontiers in Cancer Prevention Research meeting.

A full-term pregnancy at an early age is the only natural physiological condition known to significantly decrease the lifetime risk of breast cancer in women of all ethnicities worldwide. Results of this study showed that when administered 1 microgram of estradiol per day for 3 weeks, rats that had not previously borne offspring had no mammary cancers 9 months after being injected with chemical carcinogens.

"We found that daily sustained treatment with pregnancy levels of estrogen for 3 weeks is a simple, safe, short-term, inexpensive procedure for hormonal prevention of mammary cancer," according to Rajkumar Lakshmanaswamy, research assistant in the cancer research laboratory and lead investigator of the study which was conducted in Nandi Laboratory at the Cancer Research Laboratory, University of California at Berkeley. "This procedure is as effective as full-term pregnancy, removal of the ovaries or long-term tamoxifen treatment, without any loss of ovarian function including the potential for future successful pregnancies and lactation."

Full-term pregnancy in humans, as well as rats, results in a long-term decrease in blood levels of growth hormone and prolactin, resulting in a reduced promotional environment for development of breast cancer. The study ...