O-6-METHYLGUANINE IN BLOOD LEUKOCYTE DNA-AN ASSOCIATION WITH THE GEOGRAPHIC PREVALENCE OF GASTRIC-CANCER AND WITH LOW-LEVELS OF SERUM PEPSINOGEN-A, A MARKER OF SEVERE CHRONIC ATROPHIC GASTRITIS

摘要: Using a competitive repair assay, 407 samples of peripheral blood leucocyte DNA from randomly selected subjects in 17 populations were tested for the presence of the adduct O-6-methylguanine. With a limit of assay sensitivity of 0.05 fmol/mu g DNA, the adduct was detected in 21 samples (5%). Sixteen positive samples came from 102 tested (16%) from two populations, in Japan and Portugal, with extremely high gastric cancer rates. This was significantly higher (P < 0.001) than the three positive samples out of 216 tested (1%) from populations with low or intermediate rates of gastric cancer. There was also an association between presence of the adduct and having a low (< 25 ng/ml) level of serum pepsinogen A, a marker of severe chronic atrophic gastritis. These results are consistent with the general involvement of methylating agents in the pathogenesis of gastric cancer and with the model proposing …