Did your mother smoke during pregnancy?
You may think that this is an insignificant question, but it actually it is a very relevant question. Women whose mothers smoked while they were pregnant are found to have reduced risk of developing breast cancer.
This certainly does not mean that you should start smoking when you are pregnant, since the very small reduction in breast cancer would be offset by the large number of other diseases caused by smoking as per Dr. William C. Strohsnitter from Tufts-New England Medical Center, Boston who lead th e research.
This finding may be connected to decreased levels of estrogen, which in turn is linked to breast cancer risk.
"Clinical studies show that maternal cigarette smoking reduces pregnancy estrogen levels," says Strohsnitter "Women prenatal exposed to maternal cigarette smoke may, therefore, have a lower breast cancer risk."
This research report is based on an analysis of data from the National Cooperative DES Adenosis project, a follow-up study that examined the health outcomes in women exposed in the uterus to diethylstilbestrol (DES), a drug later found to have harmful effects. Researchers collected data on participant's mothers regarding their smoking habits during pregnancy. The investigators then compared the rates of breast cancer among some 4000 women who were or were not exposed to maternal cigarette smoke before they were born.
When the data is analyzed after adjustment for other risk factors, women exposed in the uterus to cigarette smoke had approximately half the breast cancer rate as those not exposed.
The association was more apparent among women whose mothers smoked no more than 15 cigarettes per day than among those whose mothers were heavier smokers. However, there were too few heavy smokers to precisely estimate a dose-response relationship.
SOURCE: Epidemiology, May 2005.