EGFRvIII expression in head and neck squamous cell carcinoma: clinical significance and sources of frequency variation across studies.

EGFRvIII is a tumor-specific, gain-of-function mutation of the EGFR gene that was first detected in 1990 in glioblastoma. For the past two decades, its significance in head and neck cancer has been intensely debated, both in terms of its clinical implications and its mere presence in the disease. This review aims to synthesize evidence on the prevalence, frequency, detection methods, and clinical significance of EGFRvIII in head and neck cancer studies. Our search included major databases such as PubMed, Embase, and Web of Science with keywords such as EGFRvIII, EGFR variants, and head and neck cancer, and stratified the results using Boolean logic to enhance relevance and specificity. Data extraction involved classifying studies by detection method, anatomic subsite, etiology, geography, and population size. The results revealed a frequency of EGFRvIII expression ranging from 0 to 75% across studies, with the major factors influencing this variation being technical sensitivity and specificity issues, primer set variability, sample type and quality heterogeneity, low prevalence and statistical power, and the lack of validation standards. There appears to be an association with a poorer clinical prognosis, though the association with survival remains inconsistent across studies. For future research, it is preferable to be informed about methodological rigor and orthogonal diagnostic assays with extensive prospective validation. Understanding EGFRvIII's genuine frequency and prognostic utility in HNSCC will help guide biomarker development and targeted therapies.