How many cancer deaths could New Zealand avoid if five-year relative survival ratios were the same as in Australia?

Aim: To determine how many Māori and non-Māori deaths might have been avoidable if cancer survival in New Zealand were as high as in Australia.

Methods: Age-sex-tumour specific five-year relative survival ratios were calculated for cancer patients diagnosed with 27 tumour sites (representing about 92% of all cancers) in 2006-10. These were used to estimate the number of Māori, non-Māori and total deaths (and proportion of excess deaths) that would have been avoidable within five years of diagnosis had New Zealand's relative survival been equivalent to Australia's.

Results: A total of 3,631 cancer deaths (726/year; 13.4% of excess deaths) could have been avoidable. Among 25 tumours where ethnic-specific results were estimated, there were 851 potentially avoidable deaths in Māori (24.9%) and 2,758 in non-Māori (11.8%). Breast, bowel, lung and prostate tumours made up 64% of avoidable deaths. Those with the highest proportions of avoidable deaths were thyroid (44.7%), prostate (35.5%), breast (30.0%) and uterus (23.5%). More than 50% of Māori melanoma, prostate, testis and thyroid cancer deaths were avoidable.

Conclusion: A significant number of cancer deaths could be avoidable if New Zealand achieved Australia's relative survival ratios. The proportion is much higher for Māori than for non-Māori.

Implications: There is considerable scope to improve cancer outcomes in New Zealand.