HER2 heterogeneity in gastric/gastroesophageal cancers: From benchside to practice

Figure 1 Diagnostic algorithm for HER2 status evaluation in gastric and gastroesophageal adenocarcinomas. Immunohistochemistry (IHC) represents the initial testing method. IHC score 0 and 1+ are considered negative while score 3+ cases are considered positive and do not need further testing. Fluorescence in situ hybridization testing is required only for equivocal IHC score 2+ cases. On the basis of HER2 (red spots): CEP 17 (green spots) ratio (< 2 vs≥ 2) patients are eligible or not to anti-HER2 therapy.

Figure 2 Heterogeneity of HER2 expression in gastric and gastroesophageal cancer. A: Gastric carcinoma, intestinal type, with HER2 overexpression (score 3+; left side) vs HER2 negativity (score 0, right side). Magnification 10 x; B: Gastroesophageal carcinoma with HER2 equivocal positivity (score 2+; left side) vs negativity (score 1+; right side). Magnification x 25.