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Tuesday, April 29, 2008

Indigenous Polynesian Peoples Have Higher Cancer Mortality Rates

People who are natives of Hawaii and New Zealand have higher mortality rates for many types of cancer than do the European people who live there. This could be improved by educational programs related to screening, diet, and smoking, according to the first in a series or Reviews on worldwide cancer disparities released on April 28, 2008 in The Lancet Oncology.

Polynesia is a group of over 1,000 small islands in the Pacific Oceanic region. They extend from Hawaii in the north, to Easter Island in the east, and New Zealand in the south. To investigate the distribution of cancers in the populations of the region Dr. Gabi Dachs, University of Otago, Christchurch, New Zealand, and colleagues performed a review of cancer incidence, survival, and mortality in Polynesian populations.

They pointed out several key observations. For one, in New Zealand, cancer incidence in Maori women was slightly higher than in New Zealanders of European ancestry, while in Maori men it was slightly lower. In Hawaii, a similar relationship was found between native and non-native Hawaiian men and women. "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 Maori, but not in non-Maori populations."

In New Zealand, the overall cancer mortality rate is higher in Maori and Pacific people than in those of European ancestry. In cancers other than colon, brain, and bladder cancer or melanoma, the site specific mortality is also higher in Maori and Pacific people. For colorectal cancer, mortality is similar even though incidence is lower in Maori people. Mortality for breast and prostate cancer is higher in Maori and Pacific people than European New Zealanders, despite lower incidence in the former groups.

Lower income and socioeconomic status was linked to a higher cancer mortality, and Maori and Pacific people generally had lower incomes than European New Zealanders are. In Hawaii, a similar pattern was seen. Cancer survival was higher in Europeans living in New Zealand and Hawaii than in the natives of these islands.

When examining risk factors, Maori people had the following characteristics in comparison to European New Zealanders: they were twice as likely to be smokers, 50% more likely to be obese, and three times as likely to be obese smokers. An examination of risk factors in Hawaiians showed a slightly higher smoking incidence in natives than in Europeans, but a significantly higher risk of cancer for smoking history. This suggests that they may be more susceptible to carcinogens in cigarette smoke. Minimal legislation on tobacco in developing countries means that tobacco companies have been targeting many Pacific islands. Additionally, a higher proportion of Maori people have hepatitis B compared with European New Zealanders, a known risk factor for liver cancer. Other risk factors, including hormonal effects, growth factors, and genetic effects are also discussed in the review.

Maori people often presented with more advanced stages of cancer than European New Zealanders. Additionally, screening programs were observed to cover more European New Zealanders than Pacific or Maori people. For example, breast cancer screening covered 62% of European New Zealanders, but only 42% of Pacific women and 41% of Maori women. Treatment options also affected outcomes, and the authors examine New Zealand's government drug funding agency's, PHARMAC's, decisions not to fund bupropion to aid smoking cessation, as well as not to fund adjuvant cisplatin based chemotherapy. Both of these decisions were called into question, as they have been heavily criticized for discriminating against Maori and Pacific people, who are more likely to smoke and get lung cancer. In order to tackle cancer disparity, 23 projects were started as part of the the New Zealand Cancer Control Strategy Action Plan in late 2005. 17 have reported thus far, and many of the recommend specific services for Maori people along with a Maori cancer workforce.

The authors observe that these findings provide many further directions for policy and research." The extent of the differences in outcome due to different extrinsic risk factors, biological factors, or health behaviors 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 programs, diet, and smoking, all of which could lower the cancer burden in Polynesian communities."

Dr. John Seffrin, CEO, American Cancer Society, Atlanta, GA, USA, contributed an accompanying Reflection and Reaction comment, in which he emphasizes the need to provide proper cancer control policies in all populations. He says: "Evidence-based action can control cancer to create a new reality for all people everywhere.... All individuals, organizations, and countries need to recognize 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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