Clinical significance of HER2 overexpression in gastric and gastroesophageal junction cancers

Clinical Significance of HER2 Overexpression in Gastric and Gastroesophageal Junction CancersObjectives: In this study, we investigated the rate of HER2 overexpression in gastric and gastroesophageal junction cancers (GC, GEJC), and the relationship with HER2 expression and clinical, pathological parameters and prognosis.Materials and Methods: Surgery or biopsy specimen of 285 (202 male, 83 female) patients with GC or GEJC, the presence of HER2 overexpression by immunohistochemistry and silver insitu hybridization (SISH) were evaluated. The relationship between HER2 pozitivity and tumor size, histopathology, grade, serosal invasion (SI), lenfovaskular invasion (LVI), perineural invasion (PNI), Lauren and Borrmann type, tumor location, TNM stage, the development of local recurrence and metastatisis during follow up and survival (OS) were investigated.Results: IHC scores were; 194 (68.1%) IHC 0, 34 (11.9%) IHC +1, 30 (10.5%) IHC +2, 27 (9.5%) IHC +3. 12 of 30 (4.2%) patients with IHC +2, SISH positive, and 18 patients SISH negative. The number of patients evaluated with IHC +3 or IHC +2 and SISH (+), HER2 positivity was 13.7%. There was no relationship between HER (+) and the age, gender, TNM stage, tumor size and localization, development of LN and M, LVI, PNI, Borrmann type. HER2 (+) was higher in intestinal type tumors than in diffuz type (16.7% vs 6.9%, p=0.075). HER (+) was significantly higher in well-moderate diferantiated tumors than poorly diferantiated tumors (p=0.001). 19.4% of adenocarcinomas, 4.2% of signet-ring cell carcinomas, 10% of mixed adenocarcinoma-signet ring cell carcinomas were HER (+) (p=0.013). HER2 pozitivity was no significant effect on OS (p=0.81). But the early-stage HER2 (+) patients, median OS was shorter than advanced stage (p=0.022).Conclusion: HER2 positivity is associated with the degree of tumor differantiation and histopathology in GC and GEJC. Patients with early-stage, HER2 positivity is related to poor prognosis.