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RESEARCH PRODUCT

Correlation between classical prognostic factors and overexpression of HER2 and HER3 in localized gastric cancer

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e14589 Background: Although HER2 overexpression has been identified as a predictive factor for targeted therapy in advanced gastric cancer (GC), little is known about its role in localized GC. Recent studies suggest that not only HER2 but also HER3 might have a role in prognosis in GC. Our study aimed to identify the prevalence of HER2 and HER3 overexpression in a series of localized GC and to describe correlations of these with traditional prognostic factors Methods: We performed a retrospective analysis of HER2 and HER3 overexpression in archived tumour samples in pts diagnosed with GC at stage I-III. HER2 was assessed with herceptest, (negative if 0 or 1+, or positive with 2+ or 3+). Staining of HER3 was determined with the Rajkumar score (HER3+ when score > or = 8). Correlation between the HER receptors expression and the clinicopathologic parameters was statistically analyzed. Statistical analysis of the correlation of HER2 and HER3 with other variables was performed with chi-square test or with the Mann Witney U for continuous variables. Impact on survival was analysed with Kaplan-Meier and log-rank tests. Results: From Jan 2003 to Sep 2011, 125 patients with clinical stage I-III GC were included. Median age was 73 years (35-91) and most frequent location was antrum (47.2%). Up to 43.2% of the patients were treated with preoperative chemotherapy. HER2 was + in 18 patients (14.4%) and HER3 in 38 (30.4%). HER2 was more likely to be overexpressed in older patients (median age: 78.4 vs 68.4; p<0.0001) and in low grade adenocarcinomas (grade 1-2: 13.8% vs grade 3: 1.1%; p=0.006). HER3 was more frequently overexpressed at advanced stages (I and IIA: 10.3% vs IIB and III: 20.3%; p=0.004) and in adenocarcinoma with intestinal subtype (intestinal: 21.4% vs difuse/mixed: 8.5%; p=0.03) or without evidence of signet ring cells (absent: 26.8% vs present: 4.1%; p=0.03) . HER2 and HER3 were significantly related (p=0.0012) with an OR of 3,52 times more frequently HER3+, if HER2 was +. No significant impact was shown in survival for either HER2 or HER3. Conclusions: HER2 and HER3 overexpression seems to identify a particular subgroup of patients with favourable classical prognostic factors.