Introduction: Estrogen receptor (ER) expression in breast epithelial cells has potential as a risk marker for development of breast cancer and as a response marker for preventive interventions.
Aim: The purpose of this study was to determine if ER expression in benign cytologic specimens acquired by random periareolar fine needle aspiration (RPFNA) increases with morphologic abnormality as has been reported for histologic preparations.
Methods: ER expression was assessed in 122 women at high risk for development of breast cancer who had RPFNA hyperplasia +/- atypia and were being screened for entry into one of two chemoprevention trials. ER was assessed using antigen retrieval at 90 degrees C for 2 min and the DAKO ER monoclonal antibody (Clone number 1D5). The proportion of cells with definitive staining at each intensity level (0-4) was recorded as a percentage of the total cells counted, to give a weighted intensity score (IS).
Results: Of 122 women, 65% exhibited hyperplasia and 35% exhibited hyperplasia with atypia in their RPFNA specimens. A majority (66%) of subjects had at least 10% of ductal cells exhibiting nuclear staining for ER. Median percent of cells with > or =1+ staining was 20% and the median ER IS was 0.23. There was a strong correlation between ER IS and percentage of ER positive cells (R(2) = 0.88). By univariate analysis ER IS was statistically significantly higher in women older than median age of 48 years (P = 0.025), in postmenopausal women on HRT (P < 0.017), and in women with a Masood cytomorphology index score of > or =14 (P = 0.005). On multivariable analysis, ER IS was significantly associated with postmenopausal status (P = 0.038) and cytomorphology as measured by Masood score (P = 0.043).
Conclusion: ER can be readily measured in cytologic specimens obtained by RPFNA with the use of antigen retrieval method. Further, ER expression in cytologic specimens is influenced by postmenopausal status and morphologic abnormality.