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Science Alert: Experts Respond

Global cancer comparison highlights Maori inequality – Expert reaction

Posted in Science Alert: Experts Respond on October 15th, 2015.

Cancer rates are higher for Maori than other New Zealanders, but the same is not true for other countries’ indigenous peoples, says new research.

dripThe global study, published in the journal Lancet Oncology, examines differences in overall cancer burden between indigenous and non indigenous populations in Australia, Canada, the US and New Zealand.

The authors, including Massey University researchers, find differences between the two groups vary by country and type of cancer, but New Zealand has a particularly significant divide in overall cancer rates for Maori and non-Maori.

You can read more about the research on

An accompanying commentary article from University of Otago researchers notes that poor collection of data often makes such comparisons difficult and calls for better monitoring of cancer in indigenous populations.

The Science Media Centre collected the following expert commentary

Bridget Robson, Director of Te Ropu Rangahau Hauora a Eru Pomare at the University of Otago, Wellington is a co-author of the commentary article accompanying the research. She comments:

“This study shows disparities in the incidence of largely preventable cancers between indigenous and non-indigenous populations in high income countries.

“New Zealand ranked high for inequalities in overall cancer incidence. Large differences in rates of lung cancer between Maori and non-Maori contribute to this inequality, as non-Maori had the lowest lung cancer incidence across all states in the study while Maori had the highest. This reflects a failure of New Zealand’s tobacco control strategies, which have been more successful in reducing smoking among non-Maori. We are now seeing positive trends in Maori non-smoking rates but need to find ways to accelerate this momentum towards a Tupeka Kore 2025.

“Cancers associated with chronic infections (liver, stomach, cervical) also contribute to the overall disparity in cancer incidence. These infections are also associated with socioeconomic deprivation. Preventing, detecting, and treating infections are therefore an important plank of our cancer control equity strategies.

“Breast screening targets have been met for Maori women in several regions of New Zealand, so we know equity can be achieved. Our challenge is to ensure all regions achieve optimal participation of Maori in our cervical cancer screening programme, any future developments in HPV screening, and in our bowel cancer screening developments.

“Cancer control is not high quality unless all benefit. We know it can be done.

Annabel Ahuriri-Driscoll, Lecturer in Health Sciences, Maori Health and Well-being, University of Canterbury, comments:

Is it surprising to see New Zealand rank so high in terms of inequalities compared to other countries

“Yes and no. Maori in New Zealand share a similar history of colonization and marginalization to other indigenous peoples, and the population’s access to fundamental determinants of health (e.g. income, education, employment etc) has been severely compromised, thereby impacting health status negatively. The disparities in cancer incidence between Maori and non-Maori are well established. However, that these rates are higher than other indigenous populations known to be similarly disadvantaged, is somewhat surprising.

“There is a higher level of confidence in the accuracy of New Zealand ethnicity and cancer data, which does not necessarily extend to the other countries studied. For example, the editorial by Sarfati and Robson notes the “substantial underestimation of cancer cases in indigenous populations in the USA”.

“I note that Bramley et al (2005), in their comparison of the indigenous health of New Zealand and the United States, found that “in the case of nearly every health indicator examined here, disparities experienced by Maori in New Zealand (both absolute and relative to the majority population) were more pronounced than those experienced by American Indians/Alaska Natives in the United States”. The health indicators examined included mortality rates, cause of death (including cancer), immunization, breast and cervical screening coverage, smoking, obesity and diabetes prevalence, and access to treatment services such as coronary angioplasty, dialysis and organ transplants.

“So, this study is consistent with and supported by earlier research. ”

What do you think should be prioritized to address the gaps in cancer incidence between indigenous and non-indigenous populations in New Zealand?

“I concur with the authors’ conclusion that approaches to reduce disparities in cancer incidence must be underpinned by robust surveillance/data in order to be effective. Beyond that, a multi-pronged approach is needed to address this significant health problem: improving the capacity of indigenous populations for health by reducing socioeconomic deprivation and disadvantage, and ensuring that health service access is equitable. “Research in New Zealand has shown that Maori patients with cancer have poorer cancer survival than non-Maori patients even if the extent of the disease is about the same” (Hill, Sarfati, Robson & Blakely, 2013).

“This points to some systematic and systemic differences in the way that (cancer) care is provided to Maori, which must be attended to.”

Associate Professor Diana Sarfati, Director, Cancer Control and Screening Research Group, University of Otago, Wellington, is a co-author of the commentary article accompanying the research. She comments:

“In the current edition of Lancet Oncology, researchers report on a study comparing the incidence of cancer among Indigenous populations compared with non-Indigenous in four high income countries, United States, Canada, Australia and New Zealand. They report generally lower overall rates of cancer among Indigenous compared with non-Indigenous populations in these countries with the exception of New Zealand where Maori have higher rates of cancers than non-Maori.

“The most striking finding of this study relates to the high incidence of potentially highly preventable cancers, especially those strongly related to smoking (such as lung cancer) and chronic infection (including stomach and liver cancers) among Indigenous people. In New Zealand, Maori have very high smoking rates, and are more likely to live in poverty than non-Maori. Housing overcrowding during childhood, for example, is an established risk factor for chronic infections which are strongly related to cancers of the liver and stomach later in life. In other words, childhood poverty can cast a long shadow increasing the risk of cancer in adulthood. These findings strengthen the argument for a strategic focus on the burden of cancer among Maori in New Zealand, the need for better monitoring and the development of interventions that address the underlying factors that drive cancer inequities.

“The second striking finding of this report is that it appears that the inequalities between indigenous and non-indigenous people are worse in New Zealand. In fact, New Zealand has some of the best data to monitor inequalities resulting in accurate estimations of cancer incidence for Maori while data in other countries are substantially less accurate meaning that the incidence of cancer among indigenous people in the other countries is likely to have been underestimated, possibly substantially.

“There is broad international concern about the lack of health data disaggregated for indigenous peoples. All Indigenous peoples have the right to participate in the design and implementation of cancer control planning and service delivery. Canada, Australia, New Zealand, and the United States should be better placed than many others to achieve a high standard of monitoring across the cancer care continuum.”

Dr Nina Scott, indigenous public health physician from Aotearoa/New Zealand and Chair, Hei Ahuru Mowai, National Maori Cancer Leadership Group, comments:

“Greater focus on indigenous health is a positive step toward health equity and in this light, it was a pleasure to read the article by Moore and colleagues and responding editorial by Sarfati and Robson.

“Colonisation creates and is created from, an inequity generating environment. So it is incongruous that countries with indigenous/non-indigenous inequities in life expectancy should not have corresponding inequities in cancer incidence. The anomaly of lower lung cancer rates for indigenous versus non-indigenous peoples in the USA is especially suggestive of problems with the data.

“Sarfati and Robson address the issue of poor quality ethnicity data and the previous 30% undercount of indigenous cancer incidence in New Zealand illustrates their argument brilliantly. It’s clear that a sufficiently complete ethnicity dataset is not necessarily a sufficiently accurate data set.

“As implied by all authors, Canada, Australia, New Zealand and the USA do have the resources to achieve equity in cancer incidence, survival and mortality between their indigenous and non-indigenous populations. Inequities are, by definition, preventable and fixable as well as being unfair. As a starting point, it would be encouraging to see high quality data on inequities in cancer incidence, survival and mortality between indigenous and non-indigenous groups reported nationally as a measure of national cancer control quality in all high income countries.”

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