News Release

Why is there higher cancer mortality in indigenous Polynesian peoples?

Peer-Reviewed Publication

The Lancet_DELETED

Native residents of Hawaii and New Zealand have much higher mortality rates for many cancers than the European peoples who live there. Education on screening programmes, diet, and smoking could help tackle this. The issues are discussed in the first of a series of Reviews on worldwide cancer disparities in the May issue of The Lancet Oncology.

Polynesia consists of several islands that are scattered across a vast triangle in the Pacific, and extend from Hawaii in the north, to Easter Island in the east, and New Zealand in the south. Dr Gabi Dachs, University of Otago, Christchurch, New Zealand, and colleagues reviewed cancer incidence, survival, and mortality across Polynesian populations.

In New Zealand, they highlighted that cancer incidence in M�ori women was slightly higher than in New Zealanders of European ancestry, whereas in M�ori men it was slightly lower. A similar pattern was seen in Hawaii between native and non-native Hawaiian men and women. The authors say: "Importantly, the incidence of site-specific cancers differs by ethnic group, with cervical and uterine cancer in women, and stomach and testicular cancers in men being in the top five most common cancers in M�ori, but not in non-M�ori populations."

Further, they report that in New Zealand, overall cancer mortality is higher in M�ori and Pacific people than in those of European ancestry. Site-specific mortality is also higher in M�ori and Pacific people, except for colon, brain, and bladder cancer, and melanoma. For colorectal cancer, the mortality in M�ori people is similar to that in European New Zealanders despite a much lower incidence of this cancer in M�ori people. And mortality for breast and prostate cancer is higher in M�ori and Pacific people than European New Zealanders, despite lower or similar incidences of breast cancer and prostate cancer in M�ori and Pacific people. Lower income and socioeconomic status was associated with higher cancer mortality, and M�ori and Pacific peoples had generally lower incomes than European New Zealanders. Again, in Hawaii, a similar pattern was seen, with Native Hawaiians having higher cancer mortality than Europeans living in Hawaii. Cancer survival was also higher in Europeans living in New Zealand and Hawaii than the natives of these islands.

In terms of risk factors, M�ori people are more than twice as likely to be smokers than European New Zealanders, 50% more likely to be obese, and almost three-times as likely to be obese smokers. Native Hawaiians have only a slightly higher smoking incidence than European Hawaiians, but a significantly higher risk of cancer for the same smoking history, suggesting they are more susceptible to the carcinogenic properties of cigarette smoke. Limited tobacco legislation in developing countries means that many Pacific islands are among tobacco companies’ new targets. Hepatitis B is a known risk factor for liver cancer, and a higher proportion of M�ori people have hepatitis B compared with European New Zealanders. The effects of hormones, growth factors and genetic risk factors are also discussed in the Review.

The researchers report that M�ori people often presented with more advanced stages of cancer than do European New Zealanders,and that screening programmes, eg, for breast cancer, cover more European New Zealanders (62%) than Pacific women (42%) or M�ori women (41%). Treatment options also obviously affect outcomes, and the authors discuss the decisions of the New Zealand government drug funding agency, PHARMAC, not to fund bupropion to aid smoking cessation, and not to fund adjuvant cisplatin based chemotherapy. Both decisions were questioned as they have been criticised for discriminating against M�ori and Pacific people, who are more likely to smoke and get lung cancer. To tackle the issue of cancer disparity, the New Zealand Cancer Control Strategy Action Plan was implemented in late 2005, consisting of 23 projects across New Zealand. So far, 17 have reported, with some studies recommending specific services for M�ori people, together with a M�ori cancer workforce.

The authors conclude: "The extent of the differences in outcome due to different extrinsic risk factors, biological factors, or health behaviours is unclear….Advances such as adjuvant chemotherapy for breast, bowel, and lung cancer have improved survival, but data on treatment by ethnicity are lacking, and such treatment might be unequally applied between ethnicities. Evidence exists for a benefit of culturally appropriate education on screening programmes, diet, and smoking, all of which could lower the cancer burden in Polynesian communities."

In an accompanying Reflection and Reaction comment, Dr John Seffrin, CEO, American Cancer Society, Atlanta, GA, USA, says: "Evidence-based action can control cancer to create a new reality for all people everywhere….All individuals, organisations, and countries need to recognise the immense burden of death and suffering caused by this terrible disease, and work together to achieve worldwide cancer control by ensuring equitable access to health resources for all."

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Dr Gabi Dachs, University of Otago, Christchurch, New Zealand T) +64-3-364 0558 E) gabi.dachs@otago.ac.nz

For Dr John Seffrin, CEO, American Cancer Society, Atlanta, GA, USA please contact Andrew Becker T) +1 212-237-3899 / +1 917-673-7728 E) john.seffrin@cancer.org / andrew.becker@cancer.org


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