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High Cancer Rates in Indigenous People of High-Income Countries

Indigenous people in the USA, Canada, Australia and New Zealand have high rates of preventable cancers, including lung and cervical cancer, according to research published in The Lancet Oncology.

The most commonly occurring cancers among indigenous men, irrespective of region, were lung, prostate and colorectal cancer. Among indigenous women, breast cancer was the most frequent cancer, followed by lung and colorectal cancer.

Of note were high rates of lung cancer among indigenous men in Australia, New Zealand and Alaska. Observed rates were between 44% (Western Australia) and 155% (New Zealand) higher than those observed in non-indigenous men.

Among women, lung cancer rates were also particularly high in New Zealand Māori (four times the rate observed in non-Māori) and Alaskan natives (60% higher than in white women). The incidence of cervical cancer was higher among indigenous women in most jurisdictions.

In Australia, head and neck cancers rates were up to 91% higher in indigenous men than in their non-indigenous counterparts. They were also three-and-a-half times higher among indigenous women in the Northern Territory and twice as high in Alaskan natives compared with white American women.

Despite this, the overall cancer burden was substantially lower in indigenous populations in the USA (except for women in Alaska), similar or slightly lower in Australia and Canada, and higher in New Zealand compared with their non-indigenous counterparts.

“Lower overall incidence in some countries is the result of a lower incidence of several of the most commonly occurring cancers,” explained the study’s lead author,

Dr Suzanne Moore of the Menzies School of Health Research. “The reasons for this are not well understood, but probably include competing causes of death at an early age (e.g. cardiovascular disease and diabetes) and lower frequency of cancer screening, especially for colorectal and prostate cancers. Other factors such as greater parity, earlier age at first birth and longer breastfeeding times might contribute to the lower risks of breast cancer.”

Study co-author Dr Freddie Bray of the International Agency for Research on Cancer added: “Lung cancer was the most commonly occurring cancer among indigenous populations in our study. Smoking – a major risk factor for a number of cancers, including of the lung, oral cavity, head and neck, oesophagus, stomach and cervix – appears to be highly prevalent in indigenous communities in all four countries compared to their non-indigenous counterparts.”

Writing in a linked Comment, A/Prof Diana Sarfati and Ms Bridget Robson of Otago University said: “These findings strengthen the argument for a strategic focus on the burden of cancer in indigenous people, the need for better monitoring, and the development of interventions that address the factors that drive cancer inequities”.