Trends in incidence rates of adenocarcinoma of the oesophagus and gastric cardia in New Zealand, 1978-1992

Abstract

Background. Increasing incidence rates for adenocarcinomas of the oesophagus and gastric cardia have been reported from the United States, Denmark, United Kingdom, Switzerland, and Sweden. This paper reports on the incidence of adenocarcinomas of the oesophagus and gastric cardia in New Zealand in the Maori (Polynesian), and non-Maori (predominantly European) populations. Methods. Incidence data from the National Cancer Registry for 1978 through 1992 were used to compute age-adjusted rates by sex, ethnic group, anatomic subsite, morphology, 14 area health districts, and for three periods: 1978-1982, 1983-1987 and 1988-1992. Statistical tests for significance of trends and differences in frequencies were employed. Results. Incidence rates for adenocarcinoma of the oesophagus are increasing in non-Maori men and women, but at a lesser rate than that reported for the US. The rate of 2.3 per 100,000 population (1988-1992) for non-Maori men is similar to the rate for US white men of 2.5 (1988-1990). Rates for adenocarcinoma of the gastric cardia in non-Maori men declined from 2.5 in 1983-1987 to 1.9 in 1988-1992, and were stable at 0.4 in non-Maori women. However, rates for cases with unspecified anatomic subsite fluctuated over the 15-year period and probably caused a deflation in rates in the most recent 5-year period. Conclusions. The incidence patterns of adenocarcinomas of the oesophagus and gastric cardia in New Zealand should be monitored over the next decade for confirmation of the trends observed here. There is need to review the quality of the data in the New Zealand registry.