Cancer rates have been skyrocketing among the Inuit people—a dramatic rise that researchers say can be traced to changes in smoking, diet, and other lifestyle factors, according to a review published in the September issue of The Lancet Oncology.
The Inuit (formerly known as Eskimos) live mainly in Alaska, northwest Canada, and Greenland. At the turn of the 20th century, cancer among the Inuit was very rare. Today the picture looks much different, with rates of several types of cancer rivaling—or even exceeding—those of white populations.
Although genetics and environmental factors play at least some role in the changing health picture among the Inuit, researchers say a big part of the rising cancer rates stems from the Inuit’s changing lifestyle. In the latter half of the 20th century, their society underwent major changes, transforming from a traditional hunting and fishing-based culture into modern, urban communities. Their eating habits also underwent a major shift, moving from a high-protein, fish-based diet to a high-carbohydrate, more traditional Western diet. Their intake of unsaturated fatty acids (which are thought to reduce cancer risk) dropped, while their consumption of saturated fats rose. At the same time, they became less active, and more Inuit began smoking.
“Inuit lifestyle and dietary patterns have changed extensively over the last forty years, and the effect of these changes, especially on rates of lifestyle-associated cancers (cancers of the breast, colon, and lungs) have been significant,” explains lead study author Jeppe Friborg, MD, PhD, a researcher in the Department of Epidemiology Research at the Statens Serum Institute in Copenhagen, Denmark.
As a result, researchers are seeing an emergence of cancers that didn’t exist in the Inuit a century ago. The Inuit face one of the highest incidences of lung cancer in the world—corresponding to an increase in smoking rates, and a low intake of fruits and vegetables (which are thought to protect against this type of cancer). Rates of colorectal and breast cancers have also risen sharply.
What researchers have learned so far about cancer rates among the Inuit people can serve as an important lesson for other cultures. “I think the increasing rates of lifestyle-associated cancers in the last decades among the Inuit are an example of a development seen in many populations,” Dr. Friborg says. Research into the specific risk factors affecting the Inuit could provide new insight into cancer causes for all populations.
For example, researchers can use what they are learning about the Inuit to study the development of cancers caused by viruses. The rate of nasopharyngeal cancer is 25-40 times more common in the Inuit than among other populations, and salivary cancers are 5-10 times more common. Both of these cancers are associated with the Epstein-Barr virus, which affects the Inuit at an early age.
It is also possible that certain environmental or hereditary factors may protect the Inuit from some types of cancers, including those of the prostate and bladder, which are still rare in this population. “An understanding of the gene/environment interactions responsible for these low risks would improve the understanding of causality in these cancers that are common in Western populations,” Dr. Friborg says.
Until researchers learn more about cancer causes, the focus among all peoples should be on prevention. “From a public health perspective, a reduction in smoking rates should be a main priority,” Dr. Friborg says. “Secondly, the increasing prevalence of obesity, diabetes, and physical inactivity must be dealt with.”
Friborg JT, Melbye M. Cancer patterns in Inuit populations. The Lancet Oncology. 2008;9:892-900.
Image of an Eskimo Family Group was taken in 1929 by Edward S. Curtis. Please see: www.old-picture.com.
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