A comparison of cancer statistics in New Zealand and Australia: 1996-2007

Abstract

AIM: To compare the burden and outcomes of cancer in New Zealand with those in Australia. METHODS: For the years 1996-1997 and 2006-2007, the incidence and mortality of cancer in New Zealand and Australia was compared to determine if differences between the two countries had changed over the decade under study. Summarised cancer data from New Zealand and Australia, age standardised to the 2002 World Health Organisation's standard population, were used to make the comparisons. RESULTS: For the 11 year timeframe of this study, total rates of cancer incidence reduced in New Zealand and increased in Australia. The incidence of cancer in New Zealand, relative to Australia, changed from an excess of +10.3 to a deficit of -27.5 per 100,000 people. When considering the excess in terms of gender, the annual excess of cancer registrations for New Zealand females fell from +19.9 to +0.9 per 100,000, and male cancer registration fell from an excess of +3.7 to a deficit of -58.0 per 100,000, due almost entirely to a surge in prostate cancer registration in Australia. Over the same 11-year timeframe, cancer-specific mortality rates decreased in both countries, but there was no change in the difference between New Zealand and Australian rates, which remained 10% higher in New Zealand. Similar to findings on 1996/7 data, the main cancer sites responsible for the overall excess mortality in 2006/7 were colorectal cancer in both sexes, and lung and breast cancer in females. CONCLUSION: The persisting different cancer mortality rates between the two countries is likely to have been partly due to lifestyle and ethnic differences in the populations, and partly due to New Zealanders presenting with more advanced cancers and having less easy access to some treatments. Until we know the relative contributions of these factors, it will be difficult for New Zealand to plan interventions in the future which have a good chance of lifting our cancer survival rates to those of our closest neighbour. The collection of clinical stage on all new cancer registrations would provide the base information required.