A positive association was identified for PD-L1 expression with mismatch repair deficiency and EBV status; however, no association was revealed with HER2 status.
None of the CRAs showed MMR deficiency (0.0 % vs. 5.6 %, CRA vs. CDA, p = 0.036), HER2 overexpression (0.0 % vs. 12.5 %, p = 0.001), or loss of PTEN expression (0.0 % vs. 9.7 %, p = 0.003).
Tumor RAS mutational status is helpful to determine which patients may benefit from epidermal growth factor receptor (EGFR)-directed therapies, and other novel biomarkers (BRAF, HER2, and mismatch repair deficiency) allow us to select patients who may benefit from biologic therapies that are FDA-approved for other malignancies.
EBV-positivity was mutually exclusive with MMR-deficiency, predominantly identified in male patients, and these tumors were undifferentiated with proximal location. p53 mutant type was significantly found predominantly in the EBV-negative (60.6% vs 14.3%, P=0.001) and HER2-positive (78.0% vs 56.2%, P=0.002) groups.