While perusing medline for another purpose, I found a reference to a study
published in the International Journal of Epidemiology, 1995, 24(3):499-503,
titled "Prolonged Lactation and Endometrial Cancer," by Rosenblatt, K.A.,
and D.B. Thomas.

Why do these titles always imply (to me) that bf is a risk factor?  Am I
being paranoid?  The abstract says that the risk of endometrial cancer is
related to estrogen levels, with an increased risk when estrogen levels are
high.  They look at data from six countries to assess whether breastfeeding
(lower estrogen levels) helped protect women against endometrial cancer.
They conclude: "Significant decreasing trends in risk were observed with
increasing duration of lactation, and with months of breastfeeding per
pregnancy.  Risk was lowest in women who had most recently lactated, and the
apparent protective effect declined with time since cessation of
breastfeeding, so that there was no evidence for a protective effect after
age 55 even in women who had breastfed for over five years.  The long-term
lactation that takes place in developing countries probably reduces the risk
of endometrial cancer, but this effect may not persist into the ages at
which this diesase is most common."

I got a chuckle from the assumption that only women in developing countries
nurse for years with each pregnancy....

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Katherine A. Dettwyler, Ph.D.                         email: [log in to unmask]
Anthropology Department                               phone: (409) 845-5256
Texas A&M University                                    fax: (409) 845-4070
College Station, TX  77843-4352