Is Helicobacter pylori a Poor Prognostic Factor for HER-2 SISH Positive Gastric Cancer?

Background: Helicobacter pylori (H. pylori) is one of the risk factors for gastric cancer (GC). Any prognosticeffect of HER-2 status in gastric lymph node metastasis in H. pylori positive cases is unknown. Materials and
Methods: A total of 74 patients, 47 (64%) male, and 27 (34%) female, who had subtotal or total gastrectomyand also positive lymph nodes, were included in the study. Age range was 29-87 years, and median age was 58years. HER-2 expression was assessed in both gastric resection samples and lymph node material with carcinomametastasis of the same patient by immunohistochemistry (IHC) and silver in situ hybridization (SISH) methods.H. pylori status was examined in gastric materials of all patients. Relationships between HER-2 status in gastriccancers and lymph nodes and H. pylori status were investigated.
Results: H. pylori was positive in 40 cases (54%),and negative in 34 (46%). While in the primary tissues of H. pylori positive cases, SISH positivity for HER-2was observed in 13 cases (86%), SISH negativity was observed in 2 (14%), in metastatic lymph nodes 21 cases(72%) were SISH positive and 8 cases (28%) were SISH negative (P=0.005 and P=0.019, respectively). InitialCEA values were high in 18 cases (78%) with positive H. pylori and in 5 cases (22%) with negative H. pylori(P=0.009). While SISH data of patients were negative in 59 cases (80%) and positive in 15 cases (20%) in primarytissues, they were negative in 56 cases (75%) and positive in 18 cases (25%) in lymph nodes. Discrepancy betweenprimary tissue and lymph node results was detected in 3 cases, in which SISH was negative in the primary tissueand HER-2 expression was positive in the lymph nodes.
Conclusions: Clinical progression was poor in H. pyloripositive cases with HER-2 negativity in primary gastric tissue, but HER-2 positivity in the lymph nodes. SISHpositivity can be expected in H. pylori positive cases, and it may be predicted that these cases can benefit fromtrastuzumab treatment.