ABSTRACT
Approximately 15-30% of breast cancers have amplified HER-2. AntiHER-2 directed therapies are among the first and most successful targeted therapies. These therapies have made a dramatic impact on the outcomes in breast cancer patients whose tumors have amplified HER-2 and may be useful in other tumor types as well. The amplification of HER-2 serves as both a robust prognostic and a predictive biomarker in breast cancer and will be reviewed in this chapter. More recent data suggest similar prognostic and predictive value to HER-2 amplification in gastric cancer. Also, there is evidence that HER-2 serves as a prognostic biomarker and may be a predictive biomarker in other cancers and this will be discussed more briefly.
