Digital image analysis of breast epithelial cells collected by random periareolar fine-needle aspirates (RPFNA) from women at high risk for breast cancer taking hormone replacement and the aromatase inhibitor, letrozole, for six months
Aromatase inhibitors are currently being evaluated as preventive agents in post-menopausal women at high risk for breast cancer. A phase II trial of 42 women on hormone replacement therapy (HRT) treated with letrozole for 6 months showed Ki-67 was reduced by 66% but showed no change in cytomorphology or Masood score. Subsequent image analytical procedures (karyometry) conducted on a subset of the samples captured subvisual information that showed reduced cellular abnormality after 6 months of letrozole. In the present study we expanded on the preliminary karyometry study to determine if the change in karyometric measurements corresponded to changes in risk biomarkers quantified in the Phase II trial; and secondly, whether these biomarkers might be used together to serve as markers of response in individual cases. Pap stained slides from the Phase II trial were used. Epithelial cell images were digitized on a CCD video-microphotometer and the nuclei were segmented from the field using a semiautomatic algorithm. Nine out of 37 cases analyzed showed a numerical decrease in all three markers, although only three of these exhibited changes substantial enough to be considered as an improvement. However, 12 cases showed improvement by cytology (a decrease in Masood score of at least 2), an additional 13 cases demonstrated a reduction in Ki-67 expression by 50% of the median baseline value, and an additional five cases exhibited a decrease of at least 10% in abnormal cells by nuclear morphometry. Thus, a total of 30 of 37 cases (81%) showed improvement in at least one marker. There was no correlation between changes in Ki-67%, karyometric abnormality, and Masood score change other than specimens that exhibited an improvement in cytology also displayed greater decreases in nuclear morphometry abnormalities. Given the heterogeneity of mechanisms leading to malignancy, the quantitative analysis of nuclear chromatin patterns may be valuable as a global, or integrating, biomarker of change in chemoprevention studies in conjunction with additional markers. Correlation with long term clinical outcome is needed to validate meaningful combinations of informative biomarkers.