Correlation of mammographic breast density with Ki-67 expression in benign breast epithelial cells obtained by random periareolar fine needle aspiration of high risk women

Abstract

1011 >Background: Known risk factors for breast cancer development include elements incorporated into the Gail risk model, mammographic breast density and cytologic atypia detected by Random Periareolar Fine Needle Aspiration (RPFNA). Ki-67 expression is a possible risk biomarker and is currently being used as a response biomarker in chemoprevention trials. We have previously shown that Ki-67 expression is higher in RPFNA specimens of benign breast cells exhibiting cytologic atypia. It is not known whether there is a correlation between mammographic density and Ki-67 expression in benign breast ductal cells obtained by RPFNA. Methods: 344 women at high risk of developing breast cancer (based on personal or family history) seen at The University of Kansas Medical Center high risk breast clinic, who underwent RPFNA with cytomorphology and Ki-67 assessment, plus a mammogram were included in the study. Mammographic breast density was assessed using the Cumulus program. Categorical variables were analyzed by Chi-square test and continuous variables were analyzed by non-parametric test and linear regression. Results: 40% of women were premenopausal, 7% perimenopausal and 53% were postmenopausal. Median age was 49 years, median 5 year Gail Risk was 2.2%, and median Ki-67 was 1.9%. Median mammographic breast density was 37%. Ki-67 expression increased with cytologic abnormality and number of cells collected, but was unrelated to Gail risk (as observed previously). Breast density was higher in pre-menopausal women (p=0.001), those with lower BMI (p< 0.001), and lower 5-year Gail risk (p=0.012); Breast density showed no correlation with Ki-67 expression or cytomorphology. Conclusion: Given the lack of correlation of mammographic breast density with either cytomorphology or Ki-67 expression in RPFNA specimens, mammographic density and Ki-67 expression should be considered as potentially complementary response biomarkers for breast cancer chemoprevention trials. No significant financial relationships to disclose.