[peggy]

Ella, I just read the following:

Some evidence suggests that evening primrose oil might affect the levels of estrogen in your body, though the oil's effect on estrogen has not yet been definitively demonstrated....

...according to a study published in "Menopause" in 2007. This suggests that evening primrose oil might increase estrogen levels, since it might mirror the effects of estrogen therapy for treating symptoms of menopause....

...Although the role of evening primrose oil in treating hormone-related disorders suggests it might alter the levels of estrogen in your body, as of October 2011 no study or clinical trial has carefully examined its role in regulating estrogen. As a result, it is not yet known whether evening primrose oil can cause high estrogen levels.

Source: http://www.livestrong.com/article/548301-does-evening-primrose-oil-cause-high-estrogen-levels/

And here an interesting response as regards EPO and breast cancer:

I can find no evidence suggesting that evening primrose oil has estrogen-like effects or that it increases breast cancer risk or risk of recurrence. I did come across a report suggesting that GLA might actually augment the treatment of an aggressive type of breast cancer associated with the Her-2/neu gene. Research at Northwestern University found that GLA inhibits the action of this cancer gene and also improves the response of these breast cancer cells to Herceptin, the drug used to treat Her-2/neu-positive breast cancer. (However, I've seen no confirming follow-up studies.)

If you've had breast cancer and find that evening primrose oil relieves hot flashes or is otherwise helpful to you, there's no reason not to continue using it.

Andrew Weil, M.D.

Source: http://www.drweil.com/drw/u/QAA401109/Is-Evening-Primrose-Oil-Safe-After-Breast-Cancer.html