Predictive Value of Histologic Characteristics on Hormone Receptor and HER-2 Status of Patients with Invasive Breast Carcinoma, No Special Type, in an Academic Medical Center

Objective: This study aims to assess the predictive value of histologic characteristics in determination of hormone receptor (ER/PR) and HER-2/Neu status in patients with invasive breast carcinoma of no special type (NST). Methodology: A 4-year review of histopathology and immunohistochemistry reports of women diagnosed with invasive carcinoma NST, was done. Multiple logistic regression was used to determine the association between histologic characteristics and ER and PR status, while multinomial multiple logistic regression was used to determine the association between histologic characteristics and HER-2 status, and that between ER and PR expression, and HER-2 immunoreactivity. All analyses included age, pathologic tumor size, lymph node stage, and lymphovascular space invasion as covariates.  Results: A total of 137 cases were included in the study. Architectural grade is a significant positive predictor of equivocal HER-2 status ( P =0.026). Nuclear grade is a significant negative predictor of ER status ( P =0.031). Elston score and Nottingham histologic grade showed no significant association with hormone receptor and HER-2 status. ER status demonstrated no significant association with HER-2 expression, but PR status appears to be a significant negative predictor of a strongly positive HER-2 status ( P =0.035). Lymph node stage seems to be a significant positive predictor of an equivocal HER-2 status. Conclusion: Histologic characteristics can predict ER, PR, and HER-2 status, and interactions between expression of these markers provide some insights regarding the complex genetic interactions in the pathogenesis of breast cancer, and its translation into different histologic phenotypes.