Clinicopathologic differences of gastric neoplasms between Helicobacter pylori-infected and naïve patients

Purpose: The incidence of gastric neoplasms in Helicobacter pylori (Hp) -naïve patients has recently increased due to a remarkable decrease in the Hp –infected population in Japan. We investigated the clinicopathologic differences between patients with Hp -infected gastric neoplasms (HpIGNs) and those with Hp -naïve gastric neoplasms (HpNGNs) that have not been fully elucidated so far. Methods: This retrospective study investigated 887 patients with 1010 gastric dysplasia or cancers who underwent endoscopic or surgical treatment for the recent decade. Clinical and neoplastic features were compared between HpIGN and HpNGN cases. Results: HpNGNs accounted for 4.5% (45/1010) of all gastric neoplasm cases, but were found concentratedly in the latter five-years. Nine hundred sixty-five HpIGNs included 774 differentiated-type and 191 undifferentiated-type. Forty-five HpNGNs included 4 undifferentiated type, 5 fundic-gland type, 32 foveolar type, 3 intestinal type, and 1 other differentiated type. HpNGNs occurred in significantly younger patients (59.9 vs. 71.8 years, p<0.05), were found more frequently in the proximal compartment (p<0.05), and had smaller size (median 3.0 vs. 20.0 mm, p<0.05). Histologically, HpNGNs also showed a lower prevalence of invasive cancer (13.3% vs. 41.7%, p<0.05) and lymphovascular invasion (2.2% vs. 34.9%, p<0.05) as compared with HpIGN cases. Nearly all HpNGNs (44/45, 97.8%) were diagnosed in the early pathological stage, while 17.8% (172/965) of HpIGNs were diagnosed in an advanced stage (p=0.058). Conclusions: HpNGN occurrence has recently been increasing along with an increase in Hp -naïve population and in knowledge about this type of tumor, though with a lower grade of biological malignancy regardless of histologic type.