IS4–2 - Clinicopathologic Features Predicting HER2 Overexpression in Gastric Cancer

Abstract

Background: HER2-based therapy was found to improve survival outcome of patients with HER2-positive advanced gastric cancer. Because positivity of HER2 overexpression is reported in below 20%, identifying the predictive clinical factors for the HER2 overexpression before the pathologic analysis may be helpful and cost-effective. Methods: From JAN 2005 to DEC 2010, 517 gastric cancer patients performed with HER2 IHC and/or FISH tests at Yonsei University College of Medicine were enrolled. Results: Among the 517 patients, 61 patients (11.8%) were confirmed as HER2 overexpression. 43 of 258 (16.7%) stage IV and 18 of 259 (6.9%) localized gastric cancer patients had HER2 overexpression (p <0.001). HER2 overexpression was more common in male (14.2% vs. 7.5% in female, p-value 0.024), moderately differentiated (26.4% vs. 11.1%, 8.9%, 4.9% and 5.9% in well differentiated, poorly differentiated, signet ring cell, and mucinous, p <0.001). Patients with elevated CEA (> 5.0 ng/mL vs. <5.0 ng/mL: 24.3% vs. 8.4%, p <0.001), metastasis to distant lymph node (with vs. without: 28.6% vs. 14.8%, p-value 0.042), without carcinomatosis (without vs. with: 21.2% vs. 11.6%, p-value 0.039) and pulmonary metastasis (with vs. without: 47.4% vs. 14.2%, p <0.001) also frequently had HER2-positive disease. In addition, high risk patients with 4 or more of the 7 features had 32.9% of HER2 positivity. (p <0.001). Conclusions: Those clinicopathologic factors may be helpful to predict the high likelihood of HER2 positive cases prior to pathologic confirmation in gastric cancer. Further molecular study for the HER2 overexpression is needed to clarify and explain this clinical phenomenon.