The risk of breast cancer associated with the use of synthetic progesterone known as progestins has been a topic of much controversy and concern for many years. Now a new study reports on the impact of progestins on breast cancer in animals models.
Impact of Progestins
In 2002, the large, well-known Women’s Health Initiative (WHI) Estrogen plus Progestin Study was stopped because the investigators found an increased risk of breast cancer and cardiovascular disease in women who were taking the active pills (that included progestins) compared with women taking placebo.
A subsequent study (2008) found that estrogen plus progestin HRT increased the risk that women will have abnormal mammograms and breast biopsies. Then in 2009, a new study of WHI participants found that women who stopped taking the estrogen plus progestin had a significant decline in breast cancer risk.
Now researchers at the University of Missouri have compared four types of progestins used in HRT and discovered found four distinctly different outcomes on the progression of breast cancer. The four synthetic progestins used included medroxporgresterone acetate (MPA), norgesterel (N-EL), norethindrone (N-ONE), and megestrol acetate (MGA).