HELICOBACTER-PYLORI INFECTION, SERUM PEPSINOGEN LEVEL AND GASTRIC-CANCER - A CASE-CONTROL STUDY IN JAPAN

We conducted a case-control study to evaluate the effect of Helicobact er pylori (HP) infection on the risk of gastric cancer in Tokyo, Japan . The sera at the time of diagnosis from 282 gastric cancer cases and 767 sex- and age-matched cancer-free controls were tested for the pres ence of anti HP Ige antibody (HM-CAP ELISA kit) and serum pepsinogen ( PG) level (PG I and PG II Riabead). No significant association was obs erved in all sets [matched odds ratio (OR) = 1.04, 95% confidence inte rval: 0.73-1.49]. In subgroup analysts, however, an association was su ggested in females [OR = 1.57], a younger population (< 50 years) [OR = 1.86], early cancer [OR = 1.53] and small cancer (< 40 mm) [OR = 1.5 5]. Furthermore, we observed a tendency for odds ratios to decrease wi th an increase in age or cancer growth (depth of tumor invasion and tu mor size). Considering that the spontaneous disappearance of HP due to extended mucosal atrophy may lead to these decreasing odds ratios, we applied the conditional logistic model adjusted for the PG I/II ratio as a measure of atrophic gastritis. This analysis showed a positive a ssociation with HP infection in all sets [OR = 1.69; 1.01-2.81], dista l cancer [OR = 1.88; 1.07-3.31] and intestinal-type cancer [OR = 3,76; 1.39-10.18]. We concluded that the risk of cancer associated with HP infection may be underestimated in studies with cross-sectional exposu re because of spontaneous disappearance of HP due to extended mucosal atrophy.