Epidermal Growth Factor Receptor (EGFR) is a tyrosine kinase present in gliocytes, epithelial cells, fibroblasts, keratinocytes, and other cell types. EGFR is overexpressed in various cancers including those of the colon, pancreas, oropharynx, stomach, and non–small cell lung, as well as head and neck squamous carcinoma and anal squamous carcinoma. EGFR expression is common in breast cancer, especially in triple-negative and basal-like breast carcinomas, and recent research has also found EGFR expressed in malignant bone and soft tissue cancers. Anti-EGFR is useful for detecting epithelioid and synovial sarcoma.