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4 October 2007
Daughters of older mothers face increased risk for breast cancer
MedWire News: Women are more likely to develop breast cancer if they are born to mothers over the age of 30 years, research suggests.
In a large prospective study, Fei Xue (Harvard Medical School Boston, USA) and colleagues report that women born to mothers aged 31-35 years are 17% more likely to develop breast cancer than women born to mothers aged 20 years or younger.
The father's age, however, did not affect the daughter's subsequent risk for breast cancer, leading the researchers to speculate that the effect may be caused by exposure to higher levels of estrogen in the womb.
The researchers used data from the Nurses' Health Study - a large cohort of 121,700 nurses aged between 30 and 55 years who were followed-up with mailed questionnaires between 1976 and 2002. The researchers were able to calculate parental age at birth by subtracting the parent's year of birth from the daughter's year of birth.
The mean maternal age at delivery was 28 years while the mean paternal age at delivery was 31 years.
Women born to mothers aged 21-25, 26-30, 31-35, and 36 years or older had a 8, 12, 17, and 12% increased risk for breast cancer, respectively, compared with those born to mothers aged 20 years or younger.
The researchers note that the association between advanced maternal age and higher incidence of breast cancer was more consistent in firstborn daughters who also had estrogen- and progesterone-positive tumors.
"Our findings add evidence to the hypothesis that intrauterine exposures, especially those related to maternal endogenous sex hormones, may play a role in the etiology of breast cancer," conclude Xue et al in the journal Breast Cancer Research and Treatment.
Breast Cancer Res Treat 2007; 104: 331-340
http://www.springerlink.com/content/...4bf54aeb2&pi=9