[739] HER2 Status in Gastric and Gastroesophageal Junction Adenocarcinoma: A Clinicopathologic and Prognostic Analysis from Four Chinese Clinical Centers

Weiqi Sheng, Dan Huang, Xiaoyan Zhou, Shujuan Ni, Xiang Du. Fudan University Cancer Center, Shanghai, China

Background: The purpose of this study was to analyze the incidence and patterns of HER2 expression in gastric and gastroesophageal junction cancer in China, to compare the classical hybridization method (fluorescence in situ hybridization, FISH) with the novel, fully automated brightfield dual color silver enhanced in situ hybridization (DSISH) detection, and to evaluate the relationship between HER2 status and clinicopathological features and outcome of gastric cancers.
Design: HER2 expression was investigated in 726 consecutive gastric or gastroesophageal junction cancer samples in the northern, southern, western and eastern China populations from four hospitals. All the samples were analyzed for HER2 status by immunohistochemistry (IHC), FISHand DSISH. The association between HER2 overexpression and the clinicopathologic characteristics was analyzed.
Results: On the basis of immunohistochemistry, which was applicable in 726 cases, 84 tumors (11.6%) were scored as IHC 2+ and 74 tumors (10.2%) were scored as IHC 3+. Concordance of FISH results, 94 tumors (12.9%) were HER2-amplified. Of HER2-amplified cases, 69 tumors (73%) scored IHC 3+, showing the correlation between HER2 gene amplification and overexpression (P<0.001). The DSISH assay showed a 96% concordance rate with FISH results in 726 samples (p<0.001). No significant trend was observed in four different populations of China. Ninety-one adenocarcinomas (12.5%) were HER2 positive. HER2-positive cases were more frequently found in men, gastroesophageal junction cancers, the intestinal type by Lauren classification and well to moderate differentiated cancers. There was no significant difference of 3 years overall survival between HER2 positive and negative patients.
Conclusions: These results reveal that HER2 status was reliable determined and no regional difference was observed in Chinese population. DSISH represents an excellent alternative for the evaluation of HER2 status in gastric and gastroesophageal junction cancer.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 86, Wednesday Afternoon

 

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