SIGNIFICANCE OF HELICOBACTER-PYLORI INFECTION AS A RISK FACTOR IN GASTRIC-CANCER - SEROLOGICAL AND HISTOLOGICAL STUDIES

We conducted a case-control study to examine the association of Helico bacter pylori infection as a risk factor in gastric cancer in the Japa nese population. Serum IgG antibodies for Helicobacter pylori were det ermined in 55 consecutive patients with gastric cancer and in 75 age- and sex-matched mass survey subjects and 57 age- and sex-matched cance r-free patients with conditions considered at a high risk for developm ent of gastric cancer (precancerous condition). We examined the histol ogy in all subjects and particular focus was placed on the extent of H elicobacter pylori-associated gastritis. The seroprevalence of Helicob acter pylori in gastric cancer patients (82%) and those with a precanc erous condition (89%) was significantly higher (P < 0.005) than that i n the mass survey subjects (60%). Positive relative risk associations were found for patients with gastric cancer (odds ratio, 3, with 95% c onfidence intervals of 1.69-5.33) and those with a precancerous condit ion (odds ratio, 5.66, with 95% confidence intervals 2.66-12.03). Sign ificant differences were found when comparisons were made among the ca se-control groups who were H. pylori-positive and had inflammatory cel l infiltration (P = 0.0127). The characteristics of Helicobacter pylor i in histologically examined gastric mucosa showed differences between Helicobacter pylori-infected and uninfected persons in all groups. Ho wever, for none of these groups was there a significant difference bet ween background mucosa for Helicobacter pylori-infected persons with o r without gastric cancer. Helicobacter pylori seroprevalence is strong ly associated with an increased risk of gastric cancer and with a prec ancerous condition; histological investigation did not define addition al factors that might be associated with increased cancer risk.