Human epidermal growth factor receptor-2 gene amplification in gastric cancer using tissue microarray technology

Area of Science:

• Oncology
• Molecular Pathology
• Gastroenterology

Background:

• Gastric cancer exhibits variable human epidermal growth factor receptor-2 (HER2) expression.
• Accurate HER2 status assessment is crucial for targeted therapy selection in gastric cancer.

Purpose of the Study:

• To evaluate HER2 status in primary gastric tumors and matched lymph node metastases.
• To compare immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH) for HER2 assessment.
• To investigate the relationship between HER2 status and clinicopathological features.

Main Methods:

• Analysis of 120 primary gastric carcinomas and 45 matched lymph node metastases using tissue microarrays.
• Assessment of HER2 overexpression by IHC and HER2 gene amplification by CISH.
• Correlation of HER2 status with clinicopathological data.

Main Results:

• HER2 overexpression was observed in 20% of gastric tumors via IHC.
• HER2 gene amplification was detected in 15.8% of tumors by CISH, with high concordance with IHC results (95%).
• HER2 amplification was associated with the intestinal phenotype but not with grading, staging, or survival.

Conclusions:

• HER2 gene amplification is the predominant mechanism for HER2 protein overexpression in gastric cancer.
• HER2 status, particularly gene amplification, is generally preserved in lymph node metastases.
• IHC and CISH are reliable methods for assessing HER2 status in gastric cancer and its metastases.