In a population-based study reported in The Lancet Oncology, Suzanne P. Moore, PhD, of Charles Darwin University, Northern Territory, Australia, and colleagues compared cancer incidence in indigenous people in Australia, New Zealand, Canada, and the United States with the incidence in nonindigenous counterparts.1 The overall rate of cancer in indigenous populations was lower in the United States except in Alaska, similar or slightly lower in Australia and Canada, and higher in New Zealand.
Study Details
In the study, incidence data were derived from population-based cancer registries in Queensland, Western Australia, and the Northern Territory in Australia, New Zealand, Alberta in Canada, and Contract Health Service Delivery Areas in the United States; the U.S. regions used in comparisons consisted of Alaska, the United States except Alaska, Northern Plains, Pacific Coast, East, and Southwest. Data for First Nations and Inuit in Alberta were provided directly by Alberta Health Services.
Age-standardized rates by registry, sex, cancer site, and ethnicity were compared for all incident cancer cases (except nonmelanoma skin cancers) diagnosed between 2002 and 2006. Rates were compared for the indigenous and nonindigenous populations of each jurisdiction, except for comparison of the Alaska Native population with the white U.S. population. The analysis included 24,815 cases of cancer in indigenous people and 5,685,264 in nonindigenous people from all regions (except Alberta).
Cancer Risk
The overall rate of cancer in indigenous populations was lower in the United States except in Alaska, similar or slightly lower in Australia and Canada, and higher in New Zealand compared with non-indigenous counterparts. Among women, standardized rate ratios for all cancers combined were higher for Alaska native women (1.30, 95% confidence interval [CI] = 1.21–1.40) and Māori women (1.29, 95% CI = 1.24–1.33), similar in Alberta (1.00), Queensland (0.92), and Australia-Northern Territory (1.01), and lower in Western Australia (0.86), U.S. Southwest (0.65), U.S.-Northern Plains (0.51), U.S.-Pacific Coast (0.50), U.S.-except Alaska (0.49), and U.S.-East (0.27).
Among men, standardized rate ratios were higher for Māori men (standardized rate ratios = 1.07, 95% confidence interval = 1.03–1.11); standardized rate ratios were lower for indigenous populations in the U.S.-East (0.27), U.S. except Alaska (0.44), U.S.-Pacific coast (0.45), U.S.-Northern Plains (0.54), U.S.-Southwest (0.57), Western Australia (0.73), and Queensland (0.80) and similar for Alberta (0.98), Australia-Northern Territory (0.96), and Alaska (0.98).
In women, breast cancer was the most common cancer in all regions except Alberta (colorectal cancer). In men, lung cancer was the most common cancer in New Zealand, all Australian regions, and Alaska; prostate cancer was the most common in other U.S. regions; and colorectal cancer was the most common in Alberta. Standardized rate ratios for lung cancer were higher in indigenous men in New Zealand (2.55), Queensland (1.77), Australia-Northern Territory (1.64), and Alaska (1.45). standardized rate ratios for breast cancer in women were lower in all indigenous populations except New Zealand (1.23) and Alaska (1.14). The incidence of cervical cancer was significantly or nonsignificantly higher in indigenous women in most regions.
The investigators concluded: “There are clear differences in the scale and profile of cancer in indigenous and nonindigenous populations in Australia, New Zealand, Canada, and the United States. Our findings highlight the need for much-improved, targeted programs of screening, vaccination, and smoking cessation, among other prevention strategies. Governments and researchers need to work in partnership with indigenous communities to improve cancer surveillance in all jurisdictions and facilitate access to cancer data.” ■
Disclosure: The study was funded by the International Agency for Research on Cancer–Australia Fellowship. For full disclosures of the study authors, visit www.thelancet.com.
Reference
1. Moore SP, Antoni S, Colquhoun A, et al: Cancer incidence in indigenous people in Australia, New Zealand, Canada, and the USA: A comparative population-based study. Lancet Oncol 16:1483-1492, 2015.
