Clinical significance of intratumoral HER2 heterogeneity in gastric cancer

Considering the high incidence of intratumoral HER2 heterogeneity in GC, accurate HER2 assessment would require larger tissues and more detailed guidelines. The guidelines should include the recommendation that FISH-scoring areas be selected with reference to a corresponding IHC slide. Also, the definition of HER2-positive tumours should be reassessed considering the intratumoral heterogeneity.