Cancer of the large bowel in a defined population: Canterbury, New Zealand, 1970--4.

A total of 1024 new cases of cancer of the large bowel occurred in Canterbury, New Zealand (population 400,796), in the 5 years 1970--4. Of these, 992 were diagnosed before death and are reviewed in this paper. The high incidence of this disease in New Zealanders of European origin is illustrated. A significant difference in site distribution of primary tumours between the sexes was found, with a female preponderance of cancer of the proximal colon gradually changing to a male preponderance of cancer of the rectum. In all, 61.5 per cent of the patients had lymph node metastases or advanced disease at the time of diagnosis or treatment. Largely as a consequence of this, only 65 per cent were able to have potentially curative treatment. The estimated crude 5-year survival rate of the whole group was 32.7 per cent (relative rate 42.8 per cent) and the crude 5-year survival rate after potentially curative surgery was 48.4 per cent (relative rate 62.4 per cent). The results are compared with those of other authors. They emphasize the generally unsatisfactory outcome of treatment.