A University of Auckland study, just published in the New Zealand Medical Journal, compares the survival of cancer patients diagnosed between 2006 and 2010 in New Zealand and Australia where similar data and health care systems operate. Both countries also have similar training programmes for health professionals.
The study, led by Professor Mark Elwood, a professor of cancer epidemiology at the University of Auckland, investigated identical period survival data for 18 cancers that accounted for more than 50 deaths per year in New Zealand.
Cancer survival (from time of diagnosis), was found to be lower in New Zealand than Australia with five-year relative survival at 4.2 percent lower for women and 3.8 percent lower for men (for all cancers).
Of 18 cancers, 14 showed lower survival in New Zealand, the exceptions being melanoma, myeloma, mesothelioma and cervical cancer.
“For most cancers, the differences in survival were greatest at one year after diagnosis, becoming smaller later on,” says Professor Elwood. “Only for breast cancer, did the survival difference increased with time after diagnosis.”
“The lower survival in New Zealand and the higher mortality rates shown in research published earlier this year, suggest that further improvements in recognition, diagnosis, issues of early management in primary care and time intervals to diagnosis and treatment may be particularly important,” he says.
In New Zealand, the difference for all cancer combined equates with about 341 deaths each year for men and 364 deaths each year for women. This is calculated as deaths from cancer in five years from diagnosis, taking into account background mortality from other causes.
This is 11.7 percent of cancer deaths within five years of diagnosis in men and 12.1 percent in women.
“These estimates are approximate and may be conservative,” says Professor Elwood. “A fuller assessment would use ethnic and age-specific comparisons.”
Comparisons of cancer survival to investigate international differences (already published) have been conducted in Europe (eg EUROCARE) and extended globally with the CONCORD study that looked at Australia, but not New Zealand.
“In the international comparisons, Australia shows very good overall cancer survival outcomes similar to those from Canada and Sweden, and better than those in the United Kingdom and Denmark,” says Professor Elwood. “Cancer survival has improved substantially in both Australia and New Zealand over recent years.”
The lower survival in New Zealand than in Australia is seen for most cancers, including for the leading causes of cancer death – lung and colorectal cancers,” he says. “This suggests a health system issue rather than a biological or treatment issue specific to certain types of cancer.”
“The demonstration of these substantial survival deficits compared to a neighbouring country should stimulate local and national, clinical and health management, attention and actions,” says Professor Elwood.
“The pattern of survival differences seen for most cancers, (apparent in the first year from diagnosis and continuing at 5 and 10 years without change), strongly suggests the reasons relate to diagnosis and initial presentation,” he says. “These relate in turn to awareness of symptoms, time intervals to referral, investigation, and diagnosis.”
This pattern of survival differences, when also seen in European and international comparisons, has resulted in international efforts to improve the early management of patients in primary care and referral processes, he says.
Professor Elwood is conducting a related University of Auckland study of the investigation of cancer symptoms by GPs. This is a national survey linked to the International Cancer Benchmarking Partnership, an organisation set up to investigate reasons for the differences in cancer survival between different countries. It will be completed early next year and is funded by the Faculty of Medical and Health’s Research Development Fund.
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