Association between HER2/neu overexpression and calcifications in breast cancer

Abstract

579 Background: HER-2/neu overexpression is an important parameter that influences prognosis and treatment for breast cancer. The purpose of this study is to explore the relationship between HER-2/neu overexpression and calcifications identified by either mammographic imaging or histologic examination. Methods: A retrospective review of the prospectively collected database was performed to evaluate the mammographic and histologic characteristics of all cases of invasive breast cancers diagnosed between 2003 and 2008. HER-2/neu positivity was defined as either overexpression by FISH analysis or 3+ staining on immunohistochemistry. Results: Of 502 invasive cancers, 165 (33%) had calcifications on mammography and 337 (67%) did not. HER-2/neu positivity was found in 63 (38%) of the calcification cases and 40 (12%) of the non-calcified cases (p < 0.001). This association persisted across all age groups and races and was independent of tumor size, nodal status, or hormone receptor status. Calcifications seen histologically also correlated with HER-2/neu overexpression, but the relationship was more complex. Among 155 cases with histologic calcifications seen within a ductal intraepithelial neoplasia (DIN) component, there were 45 (29%) that were HER-2/neu positive, compared with 67/414 (16%) that did not have calcifications within DIN (p < 0.001). If the calcifications were only within invasive tumor, the rate of HER-2/neu overexpression was less, 9/63 (14%). Univariate analysis demonstrated that tumor grade, necrosis, lymphovascular invasion and hormone receptor negativity were significantly associated with HER-2/neu overexpression (all p < 0.01). Multivariate logistic regression showed only the following factors to be significantly associated with HER-2/neu overexpression: grade of invasive tumor, presence of necrosis, progesterone receptor negativity in either the invasive or the in situ component, and mammographic calcifications. Conclusions: Recognition of the strong association between HER-2/neu overexpression and mammographic calcifications may have clinical usefulness and could lead to a better understanding of the underlying tumor biology of this important tumor marker. [Table: see text]