Cyclin D1 gene amplification is highly homogeneous in breast cancer.

Background Cyclin D1 (CCND1) gene amplification is a molecular key alteration in breast cancer and was suggested to predict resistance to antihormonal therapy. As tissue heterogeneity may affect diagnostic accuracy of predictive biomarkers, CCND1 genetic heterogeneity was assessed in this study. A novel tissue microarray (TMA) platform was manufactured for this purpose.