Public release date: 8-Oct-2007
PORTLAND, Ore. – In a study of the maternity records of more than 6,000 women, David J.P. Barker, M.D., Ph.D., and Kent Thornburg, Ph.D., of Oregon Health & Science University discovered a strong correlation between the size and shape of a woman’s hips and her daughter’s risk of breast cancer. Wide, round hips, the researchers postulated, represent markers of high sex hormone concentrations in the mother, which increase her daughter’s vulnerability to breast cancer.
The study, carried out with colleagues in Finland and the United Kingdom., is described in an article just published online by the peer-reviewed American Journal of Human Biology. The authors followed up on 6,370 women born in Helsinki from 1934 to 1944 whose mothers’ pelvic bones were measured during routine prenatal care. The study found that breast cancer rates were more than three times higher among the women in the cohort, born at or after term, whose mothers had wide hips. They were more than seven times higher if those mothers had already given birth to one or more children.
A woman’s vulnerability to breast cancer, the study found, was greater if her mother’s “intercristal diameter” – the widest distance between the wing-like structures at the top of the hip bone – was more than 30 centimeters, or 11.8 inches. The risk also was higher if these wing-like structures were round. The breast cancer risk was 2.5 times higher for the daughters of women in whom the widest distance was more than 3 centimeters greater than the distance at the front.
The OHSU study published today proposes that breast cancer is initiated in the first trimester of a pregnancy by exposure of the embryo’s developing breast tissue to the mother’s circulating sex hormones. The primary mammary cord, which gives rise to milk-producing breast lobules, develops in the fetus at 10 weeks. The fetal breast is known to be stimulated by circulating hormones; the intensity of the stimulation is such that half of all newborn babies have breast secretions.
“Our findings support the hypothesis that wide round hips reflect high levels of sex hormone production at puberty, which persist after puberty and adversely affect breast development of the daughters in early gestation,” the authors commented. They could only speculate, they said, on the exact nature of this adverse effect but pointed out: “Catechol estrogen, a metabolite or estradiol, is thought to cause chromosomal instability by breaking DNA strands. High catechol estrogen concentrations in the maternal circulation could produce genetic instability in differentiating breast epithelial cells, which would make the breast vulnerable to cancer in later life.”