Expression of c-erbB2, cyclin D1 and estrogen receptor and their clinical implications in the invasive ductal carcinoma of the breast

Background: C-erbB2 and estrogen receptors (ER) are well known for their cell proliferative capacity. Cyclin D1 is a major downstream target of both c-erbB2 and ER. This study was designed to analyze the expression of c-erbB2, cyclin D1 and ER and their prognostic implications in invasive ductal carcinoma of the breast. Methods: The c-erbB2 status was evaluated by fluorescence in situ hybridization and immunohistochemistry (IHC) and cyclin D1 and ER were evaluated by IHC in 333 invasive breast cancer specimens. Results: The results of FISH and IHC for c-erbB2 showed 86.7% concordance. The overexpression of c-erbB2 was associated with the high expression of cyclin D1 and the negative expression of ER (P < 0.01 for both). The high expression of cyclin D1 was associated with the positive expression of ER (P < 0.01). When the group of patients who overexpressed c-erbB2 were analyzed, the patients with the low expression of cyclin D1 showed a significantly higher mortality than those with the high expression of cyclin D1 (RR = 3.2; 95% CI, 1.6-6.6). When the group of the high cyclin D1 expression was analyzed, the patients with negative expression of ER showed a significantly higher mortality than those with the positive expression of ER (RR = 2.1; 95% CI, 1.1-3.8). Conclusions: Higher expression of cyclin D1 was associated with better prognosis in patients with c-erbB2 overexpression, and positive expression of ER was associated with better prognosis in patients with high cyclin D1 expression.