Supplementary Material for: Clinicopathological Features and Prognostic Significance of HER2 Expression in Gastric Cancer

Background: HER2 positivity is reported to be <20%
in gastric cancer. Clinicopathological characteristics will be helpful
to understand the biological features of HER2-positive gastric cancer. Methods:
A total of 813 gastric cancer patients who underwent HER2 testing
between January 2005 and December 2010 were included in this study. Results:
Ninety-five (11.7%) patients had HER2-positive gastric cancer. Elevated
serum carcinoembryonic antigen (CEA) concentration [odds ratio (OR),
5.629; p < 0.001] and differentiated histology (OR, 3.717; p = 0.002)
were significant predictive factors for HER2 positivity in localized
disease. For recurrent or metastatic disease, elevated serum CEA
concentration (OR, 2.545; p < 0.001), differentiated histology (OR,
3.299; p < 0.001), pulmonary metastasis (OR, 3.321; p = 0.001), and
distant lymph node metastasis (OR, 2.286; p = 0.002) were significant
predictive factors. Median disease-free survival (DFS) was shorter in
HER2-positive patients than in others, especially in stage I or II
disease (24.7 vs. 49.2 months; p < 0.001). Among HER2-negative
patients with stage II diseases, patients who received adjuvant
chemotherapy had longer DFS than others (42.2 vs. 30.7 months; p =
0.025). Conclusions: Clinicopathological factors may be
useful in predicting the HER2 positivity of gastric cancer. Further
studies are needed to understand the molecular basis of HER2-positive
gastric cancer.

背景：据报道，胃癌中人表皮生长因子受体2（HER2）阳性率低于20%。临床病理特征有助于阐明HER2阳性胃癌的生物学特性。
方法：本研究纳入2005年1月至2010年12月期间接受HER2检测的813例胃癌患者。
结果：共计95例（11.7%）患者为HER2阳性胃癌。在局限性胃癌患者中，血清癌胚抗原（CEA）水平升高[比值比（OR）=5.629；P<0.001]及组织学分型为分化型（OR=3.717；P=0.002）是HER2阳性的显著预测因素。对于复发或转移性胃癌患者，血清CEA水平升高（OR=2.545；P<0.001）、组织学分型为分化型（OR=3.299；P<0.001）、肺转移（OR=3.321；P=0.001）及远处淋巴结转移（OR=2.286；P=0.002）均为HER2阳性的显著预测因素。HER2阳性患者的中位无病生存期（DFS）短于其他患者，尤其在Ⅰ期或Ⅱ期胃癌患者中（24.7个月 vs 49.2个月；P<0.001）。在Ⅱ期HER2阴性胃癌患者中，接受辅助化疗的患者无病生存期长于未接受辅助化疗者（42.2个月 vs 30.7个月；P=0.025）。
结论：临床病理因素可用于预测胃癌的HER2阳性状态。未来仍需开展进一步研究以阐明HER2阳性胃癌的分子机制。