HER2 expression and relevant clinicopathological features in esophageal squamous cell carcinoma in a Chinese population

Abstract

Background: Despite great progress of surgery and other treatments, the prognosis of patients with esophageal squamous cell carcinoma (ESCC) is still very poor. HER2 has strong therapeutic implications in certain cancers, such as breast cancer and gastric cancer. However, literature on the frequency of HER2 expression in ESCC is scarce. In the present study, HER2 expression and gene amplification and the association of HER2 status with clinicopathological characteristics were evaluated in a large cohort of Chinese ESCC patients.Methods: A total of 857 consecutive patients who received radical esophagectomy without neoadjuvant chemotherapy were included in this retrospective study. HER2 expression was analyzed by immunohistochemistry (IHC), and its correlation with clinicopathological parameters was assessed. In addition, 65 cases, including 13 HER2 overexpression (3+) cases and 52 HER2 equivocal (2+) cases from the 857-case cohort, were selected to construct tissue microarrays (TMAs). Another 104 ESCC cases, which included 1 HER2 overexpression (3+) case, 3 HER2 equivocal (2+) cases and 100 HER2 negative (1+/0) cases, were also selected for TMA construction. Dual-color in situ hybridization (DISH) was performed on the TMAs to assess HER2 gene amplification.Results: We found HER2 overexpression (3+) status in 1.5% (13/857) of cases and HER2 equivocal (2+) status in 6.1% (52/857) of cases. HER2 expression was significantly associated with gender. HER2 equivocal (2+) expression was more likely to occur in females (P=0.028). Regarding the 169 cases analyzed by DISH, 14 (of 14, 100%) HER2 overexpression (3+) cases, 10 (of 55, 18.2%) HER2 equivocal (2+) cases, and 0 (of 100, 0%) HER2 negative (1+/0) cases showed HER2 gene amplification. HER2 gene amplification was not significantly associated with clinicopathological characteristics such as age, gender, tumor differentiation, pT stage, pN stage, pM stage and pTNM stage (P>0.05).Conclusions: Approximately 2% of the Chinese ESCC patients had HER2 overexpression based on IHC. HER2 expression was significantly associated with gender, HER2 gene amplification was not significantly associated with clinicopathological characteristics. IHC and DISH had a high concordance rate. These results provide valuable insight for the future treatment of ESCC.