Study Suggests Absence of Link Between I.V.F. and Breast Cancer

New York Times (July 19, 2016): I.V.F. Does Not Raise Breast Cancer Risk, Study Shows, by Catherine Saint Louis: 

The use of estrogen and progesterone in in vitro fertilization has in the past stoked fears that the procedure could place patients at risk of developing breast cancer.  A retrospective analysis published in 2008 found found "a potential increase in breast cancer among I.V.F. patients older than 40."  But later studies, in Israel and Australia, suggested more of a danger for younger women.  Some believed that infertility itself might be linked to breast cancer.

Several studies conducted in recent years, however, suggest that the fear is unfounded.  The most comprehensive of these studies, published in July in the Journal of the American Medical Association, found "no increased risk among women who have undergone I.V.F."  The study likewise found no increased risk among women who had less invasive treatments for infertility.  Oddly, the study emphasized what appeared to be a reduced risk of breast cancer among women who have submitted to I.V.F. multiple times.  

The JAMA study is not conclusive.  More research needs to be conducted, including on the risk of breast cancer in postmenopausal women who have had I.V.F.