Helicobacter pylori Status May Differentiate Two Distinct Pathways of Gastric Adenocarcinoma Carcinogenesis

Background: We evaluated the phenotype of sporadic gastric cancer based on HP status and binding of a tumor risk marker monoclonal, Adnab-9. Methods: We compared a familial GC kindred with an extremely aggressive phenotype to HP-positive (HP+) and -negative (HP) sporadic gastric adenocarcinoma (GC) patients in the same community to determine if similar phenotypes exist. This might facilitate gene discovery to understand the pathogenesis of aggressive GC phenotypes, particularly with publications implicating immune-related gene-based signatures, and the development of techniques to gauge the stance of the innate immune system (InImS), such as the FERAD ratio (blood ferritin:fecal Adnab-9 binding OD-background binding). Resection specimens for the sporadic and familial group were stained for HP and examined for intestinal metaplasia (IM) and immunostaining for Adnab-9. Familial kindred specimens were also tested for the E-cadherin mutation and APC (adenomatous polyposis coli). Survival was evaluated. Results: Of 40 GC patients, 25% were HP+ with a greater proportion of intestinal metaplasia (IM) and gastric atrophy than the HP group. The proband of the familial GC kindred, a 32-year-old mother with fatal GC, was survived by 13-year-old identical twins. Twin #1 was HP with IM and Twin #2 was HP+. Both twins subsequently died of GC within two years. The twins did not have APC or E-cadherin mutations. The mean overall survival in the HP+ sporadic GC group was 2.47 +/- 2.58 years and was 0.57 +/- 0.60 years in the HP group (p = 0.01). Survival in the kindred was 0.22 +/- 0.24 years. Adnab-9 labeling was positive in fixed tissues of 50% of non-familial GC patients and in gastric tissue extract from Twin #2. The FERAD ratio was determined separately in six prospectively followed patient groups (n = 458) and was significantly lower in the gastric cancer patients (n = 10) and patients with stomach conditions predisposing them to GC (n = 214), compared to controls (n = 234 patients at increased risk for colorectal cancer but without cancer), suggesting a failure of the InImS. Conclusion: The HP+ sporadic GC group appears to proceed through a sequence of HP infection, IM and atrophy before cancer supervenes, and the HP phenotype appear to omit this sequence. The familial cases may represent a subset with both features, but the natural history strongly resembles that of the HP group. Two different paths of carcinogenesis may exist locally for sporadic GC. The InImS may also be implicated in prognosis. Identifying these patients will allow for treatment stratification and early diagnosis to improve GC survival.