Human epidermal growth factor receptor 2 status of gastric cancer patients in Asia: results from a large, multicountry study

Abstract

Aim Current estimates of the human epidermal growth factor receptor 2 (HER2)‐positivity rate in gastric cancer vary widely in the literature, and there are limited data from countries in Asia. The primary aim of this study was to conduct a clinical audit of laboratories across seven countries in Asia to determine the incidence of HER2‐positive gastric cancer in this region. Methods Pathologists were asked to collect data on patient gender, age, cancer site, specimen type, tumor spread, type and grade, HER2 test results, including protein and/or gene copy enumeration, and final HER2 status on consecutive gastric cancer cases tested for HER2 in their laboratory over a 2‐year period. Results HER2 results from 5,301 gastric cancers were submitted by 50 laboratories. The overall HER2‐positivity rate was 9.7% which, after the exclusion of China, increased to 18.1%. The rate between countries ranged from 0% to 23.1%, and from 0% to 50.0% between laboratories. An equivocal HER2 result was recorded in 19.5% of cases. Conclusion Despite the lack of centralized testing to confirm the accuracy of HER2 diagnoses, the incidence of HER2‐positive gastric cancer observed here was comparable to that reported in the literature. Nevertheless, rates were highly variable between countries and laboratories, which suggests a lack of HER2 testing expertise in gastric cancer. Given that the mortality rates for gastric cancer in Eastern Asia are the highest in the world, efforts should focus on improving HER2 testing expertise in the region so that patients receive the appropriate treatment early in their disease.

Detection of ERBB2 (HER2) Gene Amplification Events in Cell-Free DNA and Response to Anti-HER2 Agents in a Large Asian Cancer Patient Cohort

“…Strikingly, the prevalence of ERBB2 gene amplification in Asian GC (21.4 vs. 11%) and CRC (11.1 vs. 5.5%) patients is higher than in non-Asian patient samples (Figure 3A). The former observation is consistent with a large study that identified HER2 overexpression, by IHC/ISH, in 9.7% of all Asian GC patients ( n = 5,301) and 18.1% when China was excluded from the analysis, suggesting regional differences in prevalence (25). In the case of primary CRC, however, another study reported an ERBB2 amplification/overexpression frequency of only 3.3% in an Asian patient cohort ( n = 4913).…”

Impact of HER2 on prognosis and benefit from adjuvant chemotherapy in stage II/III gastric cancer patients: a multicenter observational study

“…In our investigation, the rate of HER2 overexpression determined by IHC alone was 6.7%, slightly lower than the previously reported values. HER2 overexpression is more frequent in advanced GC than in early GC 15 , 29 . This slight discrepancy can be explained by the fact that, unlike many other studies, our cohort only included patients with resectable stage II/III disease.…”

Frequency of HER2/neu Overexpression in Gastrointestinal AdenocarcinomasAn Immunohistochemical Study in A Tertiary Care Hospital

“…As per the studies available a wide range of HER2/ neu expression was observed in gastrointestinal adenocarcinomas. [6,7,8,9,10,11,12,13,14] In ToGA trial HER2 over expression of 3+ positivity was seen in 10.4% for resected samples. [2] For colorectal adenocarcinomas 3+ positivity on IHC was seen in 0.5 % cases.…”