Prevalence of HER2 overexpression and amplification in squamous cell carcinoma of the esophagus: A systematic review and meta-analysis

Accurate data on HER2 positivity in esophageal squamous cell carcinoma patients (ESCC) is lacking. We conducted a systematic review and meta-analysis (Single Incidence Rates; metarate package, R) to examine the prevalence of HER2 in ESCC. Data on in situ hybridization (ISH) and immunohistochemistry (IHC) were extracted to derive pooled prevalence estimates, characteristics of the studies were extracted for subgroup analysis. Eighteen studies with 1505 patients were identified. HER2 gene amplification by ISH were prevalent in 10 % (95 % CI 6.9 %-15 %). Prevalence of HER2 overexpression (IHC3+) and borderline HER2 expression (IHC2+) were 6 % (95 % CI: 3.5 %-8.7 %) and 10 % (95 % CI: 6.0 %-17 %), respectively. An estimated 8.6 % (95 % CI: 5.5 %-13 %) of ESCC were HER2 positive using initial IHC followed by reflex ISH confirmation of borderline HER2 expression. In conclusion: Estimated prevalence of HER 2 positivity in ESCC were 10 % assessed by ISH and 8.6 % assessed by initial IHC followed by ISH.