Cancer mortality and incidence trends comparing New Zealand and Australia for the period 2000-2007

Background and aims A previous study showed that cancer mortality in New Zealand in 1996-97 was substantially higher than that expected from Australian rates. This study compared cancer mortality and incidence in New Zealand for 2000-2007 with rates in Australia, to assess if any differences had persisted or changed. Methods The numbers of cancer deaths in New Zealand, by type of cancer, year, sex, and 5 year age group, were compared to the numbers that would have occurred if NZ rates had been the same as those in Australia. Trends over time, and also cancer incidence, were assessed. Results From 2000-2007, there were each year an average of 586 (15.1% of the total) more deaths from cancer in New Zealand women than expected from Australian rates; and 197 (4.7%) more deaths in men. There was no significant change over time in these differentials. Higher cancer mortality was seen for most common sites; the greatest excesses were for colorectal cancer in both men and women. Cancer incidence in New Zealand women was 3.3% higher, and incidence in men was 4.7% lower, than in Australia over this period; thus the higher cancer deaths in New Zealand are not due simply to higher incidence. Over this time period, cancer mortality has fallen substantially in both countries; in New Zealand, it fell from 1990 to 2007 by 20% in women and 24% in men. Conclusion Cancer mortality remains substantially higher in New Zealand than in Australia, especially for women, although mortality has reduced in both countries. While the differences in 2000-07 were slightly smaller than in 1996-97, there has been little change since 2000. The greater differences in deaths than in incidence suggest that patient survival is lower in New Zealand.