Diet, genetics, lifestyle and environmental factors could explain the higher rates of liver, stomach and gallbladder cancers.
American Indians in Minnesota and surrounding states have dramatically higher rates of colon cancer and several other types of the disease than whites, a University of Minnesota researcher and his colleagues reported Wednesday.
They found that American Indians in the Northern Plains have nearly triple the rate of liver cancer and more than twice the rate of stomach and gallbladder cancer than whites in that region, according to their studies in the journal Cancer.
At the same time, cancer rates vary widely among American Indians in different regions of the country. Those in the Southwest reported some of the lowest rates of cancer, often far below those of whites, while Native Alaskans had some of the highest rates in the country.
Numerous factors could explain the dramatic differences, including diet, genetic makeup, smoking, diabetes and environmental conditions, said Dr. David Perdue, a University of Minnesota gastroenterologist and one of the lead scientists.
"American Indians tend to be diagnosed with later stage disease," he said. "The problem with later stage disease is, it's harder to treat and harder to survive." He added that early detection and lifestyle changes "can prevent a majority of these cancers."
Perdue, who is a member of the Chickasaw Nation of Oklahoma, has specialized in research on cancer and health disparities involving Native Americans.
When compared with whites, American Indians in the Northern Plains, which includes Minnesota, had:
• 39 percent more colon and rectal cancer.
• 135 percent more stomach cancer.
• 148 percent more gallbladder cancer.
• 197 percent more liver cancer.
The Northern Plains Indians also have the highest rates of lung cancer among Native Americans in the country, the studies found.
At the same time, the breast-cancer rate is about the same among American Indian and white women in this region, the research showed. In the Southwest, however, American Indian women reported half the rate of breast cancer compared with white women.
Some of the regional and racial differences surprised Perdue. He noted that American Indians are often lumped into one group for research purposes, but that their genetic and cultural differences can play a huge role in cancer rates. "We need to know more about what's driving these rates," he said. With more study, he said, they may be able to find why some American Indians are more resistant to certain types of cancer, while others are more vulnerable.Some differences, though, are well known, he said. He noted that Indians in Minnesota tend to smoke more than those in the Southwest. They also have high rates of obesity and diabetes, which are linked to cancer. More than 78,000 American Indians live in Minnesota, according to a 2005 state estimate. "It's really important for these communities to realize that they have higher rates," he said, and put more money into cancer screening and treatment.
"It is evident from this research that much more needs to be done to close the disparity gap," he said.
Maura Lerner • 612-673-7384