Apolipoprotein E genetic polymorphism, serum lipoproteins, and breast cancer risk

Apolipoprotein E (apoE) is a polymorphic gene involved in lipid metabolism with three common variant alleles (epsilon 2, epsilon 3 and epsilon 4). The epsilon 4 allele has been associated with elevated levels of cholesterol a s well as greater risk of coronary heart disease and Alzheimer's disease. I n this case-control study we examined whether apoE genotype affected the as sociation between serum lipids and breast cancer risk. In a subset of a stu dy in western New York, 260 women with incident, primary breast cancer and 332 community controls were interviewed and provided blood samples. Polymer ase chain reaction-restriction fragment length polymorphism analyses of the apoE polymorphism were performed. Participants were classified as apoE2 (e psilon 2, epsilon 2 or epsilon 2, epsilon 3), apoE2 (epsilon 3, epsilon 3), or apoE4 (epsilon 4, epsilon 4 or epsilon 4, epsilon 3). no unconditional logistic regression was used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CI). Compared with women with the apoE3 genotype, the re were no association with the risk for women with the apoE2 (OR = 1.0; 95 % CI = 0.91 - 1.64) or apoE4 genotype (OR = 0.97; 95% CI = 0.63 - 1.54). hi gher serum levels of total cholesterol, HDL cholesterol, and LDL cholestero l were not associated with risk, either in the total sample or among subgro ups of women defined by the apoE genotype. Women with the highest serum tri glyceride levels had an increase in risk (OR = 1.63; 95% CI = 1.03 - 2.59) compared to women with the lowest levels. This effect was not apparent amon g women with the apoE2 or apoE3 genotype, but much stronger among women wit h the apoE4 genotype (OR = 4.69; 95% CI = 1.49 - 14.7). These data suggest that the apoE4 genotype may modify the association between serum triglyceri des and brest cancer risk. (C) 2000 Wiley-Liss, Inc.