Current challenges in HER2-positive breast cancer.

The introduction of trastuzumab into routine clinical practice has had a dramatic effect on the outlook for patients with HER2-positive breast cancer. Nevertheless, answers to some long unresolved questions about the optimal use of trastuzumab (such as its role in small tumors or low-risk disease, cardiac safety in the elderly, and treatment duration) have emerged only relatively recently. Moreover, with the availability of new highly effective HER2-directed therapies, including pertuzumab and trastuzumab-emtansine (T-DM1), the treatment algorithm for HER2-positive breast cancer continues to evolve. This review provides a summary of the latest evidence providing insight into the management of early and advanced HER2-positive breast cancer and delineates future perspectives of study and treatment for these patients.