Purpose: The aim of this study was to clarify the human epidermal growth factor receptor 2( HER2) positivity, clinicopathological characteristics, and survival of patients with recurrent HER2-positive gastric cancer who received S-1 adjuvant chemotherapy.
Methods: Thirty-eight patients with recurrent gastric cancer who underwent curative D2 surgery and received S-1 adjuvant chemotherapy between June 2002 and December 2011 were examined. HER2 positivity was determined as defined in the ToGA study.
Results: The positivity score was assessed by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) as follows: IHC 0 in 27 patients, IHC 1+in 4, IHC 2+/FISH-in 3, IHC 2+/FISH+in 1, and IHC 3+in 3. The HER2 positivity rate was 10.5% (4/38). HER2-positive recurrent gastric cancer was characterized by a differentiated histological feature and frequent blood vessel invasion. However, the recurrence and survival rates were not significantly different between the HER2-negative and HER2-positive tumors.
Conclusions: The HER2 positivity rate after S-1 adjuvant chemotherapy did not differ significantly between patients with recurrent gastric cancer and those with primary Stage II/III gastric cancer, suggesting that S-1 adjuvant chemotherapy was equally effective, regardless of HER2 status.