Colon and rectum cancer in the New Zealand population.

To test the hypothesis that the high rates of large bowel cancer in New Zealand were attributable to geographic location, occupation, or country of birth, we reviewed 4,760 cases registered in that country between 1964 and 1968. Analyses demonstrated that significantly high rates existed for certain rural populations, for small subsections of the immigrant population, and for certain occupations. However, the number of persons-at-risk represented in these groups collectively were not large enough to account for the high New Zealand rates.