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15 Nov 2019

Researchers have found current estimates of lifetime risks of cancer diagnosis and mortality consistently higher than when they allowed for competing causes of death.

The method used in Australia to determine estimates of lifetime risks of cancer diagnosis and mortality could lead to an overestimation of these risks, especially for men, according to University of Sydney and Bond University researchers.

Cancer registries and organisations such as the Australian Institute of Health and Welfare (AIHW), use age specific cancer incidence and mortality data in a calendar year to estimate lifetime risks of cancer diagnosis and mortality.

However, the method used to achieve these numbers assumes there are no competing causes of death, which may lead to overestimation of lifetime risk and the researchers have recommended that the more accurate methodology be adopted.

The research has been published by the Medical Journal of Australia

Dr Katy Bell from the University of Sydney’s Faculty of Medicine and Health, was senior author on the analysis, which was led by Dr Anthea Bach from West Moreton Hospital and Health Service and Dr Kelvin Lo from Westmead Hospital.

The researchers calculated their own estimates on lifetime risks of cancer diagnosis and cancer-specific death, adjusted for competing mortality, and compared their findings with the corresponding risks published by the AIHW.

“AIHW estimates were consistently higher than our competing mortality-adjusted estimates of lifetime risks of diagnosis and death for all five cancers,” Dr Bell and colleagues wrote.

“Differences between AIHW and adjusted estimates declined with time for breast cancer, prostate cancer, colorectal cancer, and lung cancer (for men only), but remained steady for lung cancer (women only) and melanoma of the skin.

“In 2013, the respective estimated lifetime risks of diagnosis (AIHW and adjusted) were 12.7 per cent and 12.1 per cent for breast cancer, 18.7 per cent and 16.2 per cent for prostate cancer, 9.0 per cent and 7.0 per cent (men) and 6.4 per cent and 5.5 per cent (women) for colorectal cancer, 7.5 per cent and 6.0 per cent (men) and 4.4 per cent and 4.0 per cent (women) for melanoma of the skin, and 7.6 per cent and 5.8 per cent (men) and 4.5 per cent and 3.9 per cent (women) for lung cancer.

The authors stressed that they were not criticising the AIHW.

Richard Juckes, Head of Health Group at AIHW said cancer risk estimates are very important and should be as accurate as possible and suitable for answering the specific question of interest.

“Different methods are appropriate for different purposes,” Mr Juckes said.

“The method used by the AIHW is best suited for international comparisons because it is able to be used for most countries and it is recommended by the World Health Organisation’s International Agency for Research on Cancer (IARC) and the International Association of Cancer Registries (IACR).

“The competing mortality method has advantages in more accurately estimating lifetime risks of diagnosis and death from cancer. However, for the purpose of international comparisons it is better to have Australian estimates calculated on the same basis as other countries than to use estimates that aren’t as comparable.”

 


Published: 15 Nov 2019