Gastric and colorectal cancers in Scotland: a study of the geographical distributions and selected associations.

The geographical distributions of gastric and colorectal cancers in Scotland were investigated by analysing the data available for those diseases in the Annual Reports of the Registrar General for Scotland. For gastric cancer, the standardised mortality ratios (SMRs) for the 234 traditional communities in 1969-73 and for the 56 districts in 1979-83 were calculated. For colorectal cancer, only the data for the latter period were available, and SMRs for that period were calculated similarly. Possible determinants on the resulting pattern of high and low SMRs were investigated. Gastric cancer was generally associated with industrial and urban environments, particularly in west central Scotland, although mortality in Dundee was high in both periods; this cancer also showed significant negative correlations with social class II. By contrast, colorectal cancer showed no strong geographical pattern, no urban-rural gradient, and no social class associations. The cancers showed a weak association with each other.