Type I receptor tyrosine kinases as predictive or prognostic markers in early breast cancer.

The type I receptor tyrosine kinase (RTK) family of proteins play an essential role in the progression of early breast cancer. Our understanding of the role of these proteins has increased over the last 20 years, however, as yet, there are still a number of unanswered questions regarding their position in endocrine resistance, chemotherapy resistance and in the biology of breast cancer. There have been, and are currently, a number of clinical trials that have examined the use of anticancer therapy such as cytotoxic drugs, and treatments that target the RTKs and signaling pathways that have been identified. There is clear evidence that molecular subtypes of cancer respond differently to different therapeutic options, which challenges the 'one size fits all' approach to chemotherapy. Here we review the human epidermal growth factor receptor family of proteins and their potential predictive or prognostic role in early breast cancer.