Intratumoral heterogeneity of HER2/neu expression and its consequences for the management of advanced breast cancer

Abstract

HER2/neu oncogene overexpression has become a paramount prognostic and predictive marker in invasive breast carcinoma [1]. Its expression is usually highly homogeneous in malignant tissue [2]. Some cases of intratumoral heterogeneity have, however, been reported [3] (Figure 1). The impact of this heterogeneity on the natural history of breast cancer and its consequences on clinical management are unknown. We report here three clinical cases illustrating the complexity of this topic.