PLASMA-LIPIDS, LIPOPROTEINS, AND MAMMOGRAPHIC DENSITIES

There is strong evidence that the risk of breast cancer in populations is influenced by environmental factors, Plasma lipids and lipoprotein s are known to be under environmental control and to have epidemiologi cal and/or biological characteristics that suggest they may be relevan t to breast cancer risk, The purpose of the study described here was t o determine whether plasma lipids, lipoproteins, and the urinary excre tion of the mutagen malondialdehyde (MDA) are associated with differen ces in breast cancer risk, We measured plasma lipids, lipoproteins, an d urinary MDA in women without breast cancer but with different degree s of density of the breast parenchyma on mammography, a strong risk fa ctor for breast cancer, Mammograms from 273 premenopausal women were d igitized to high spatial resolution by a scanning densitometer, and im ages were analyzed to quantify the extent of density, The percentage o f the breast occupied by mammographic densities was found, after contr olling for the effects of age and the Quetelet index of obesity, to be significantly associated with plasma levels of high-density lipoprote in cholesterol, low-density lipoprotein cholesterol, triglyceride, apo protein B, and urinary excretion of MDA, A multivariate model comprise d of the Quetelet index of obesity, alcohol consumption, apoprotein B, parity, daily MDA excretion, and the skinfold thickness sum accounted for 36% of the variation in breast density, These results suggest tha t differences in lipid metabolism are associated with differences in b reast cancer risk as defined by mammographic densities, These findings are consistent with several other observations that show a relationsh ip between plasma lipids, lipoproteins, and risk factors for breast ca ncer.