A critical review of HER2-positive gastric cancer evaluation and treatment: From trastuzumab, and beyond

• HER2 positive gastric cancer is associated with a specific phenotype.
• Reliable HER2 testing is mandatory for the correct use of anti-HER2 treatment.
• We review present HER2 diagnosis and directed therapies in gastric cancer.
• Future strategies for HER2 gastric cancer treatment are discussed.

Identification of the importance of human epidermal growth factor receptor-2 (HER2) status, biomarker testing and the development of anti-HER2 treatments have changed the prognosis of breast and gastric cancers. The addition of trastuzumab to chemotherapy has improved outcomes for patients with HER2-positive metastatic adenocarcinoma of the stomach and gastroesophageal junction, but some relevant issues remain to be elucidated or will emerge with new drugs. This article reviews the current state of HER2 in gastric cancer focusing on diagnostic and anti-HER2 targeted treatment issues and the role of trastuzumab in localized disease, and its combination or integration with new therapies.