Obesity, Lifestyle Changes Are Factors in the Major Increases in Colorectal Cancer Rates
WebMD Health News
Reviewed By Louise Chang, MD
June 10, 2009 -- Increasing Westernization is the likely culprit in dramatically increasing incidence rates of colorectal cancer around the world, a new study says.
The trend is related to increased consumption of fatty foods in developing countries, and less physical activity -- resulting in obesity, the American Cancer Society's Ahmedin Jemal, PhD, tells WebMD.
Jemal, an epidemiologist and co-author of the study, says more "people are eating the wrong foods and driving to work instead of walking, just not getting enough physical movement generally."
The study found that colorectal cancer incidence rates for both men and women increased in 27 of 51 international cancer registries between 1983 and 2002.
"People are eating the wrong foods," Jemal tells WebMD. "Too much food is being consumed that is high in carbs and fats."
The rise was seen mostly in economically transitioning countries, including those of Eastern Europe, most parts of Asia and some nations in South America.
The researchers say the study is the first in a peer-reviewed journal -- the June 2009 issue of Cancer Epidemiology Biomarkers and Prevention -- to present colorectal cancer incidence trends across five continents.
An accompanying editorial says the rise points to a failed early detection and prevention strategy, in addition to the failure to address dietary challenges and lifestyle changes related to urbanization, now affecting most of the world.
The editorial says despite recommendations for people to seek early detection via colonoscopy and other methods, most people disregard the suggestions that help many avoid colorectal cancer.
"Recent evidence in the United States and some other countries that the increase in [colorectal cancer] cases is stabilizing also shows an increase in the awareness for timely screening," Asad Umar and Peter Greenwald of the National Cancer Institute write in the editorial.
The increases in colorectal cancer incidence rates in economically transitioning countries most likely reflect changing dietary and physical activity patterns, Jemal tells WebMD.
The new study, led by ACS epidemiologist Melissa Center, MPH, reviewed colorectal cancer incidence data from 51 cancer registries around the world with long-term information from the Cancer Incidence in Five Continents databases, created by the International Agency for Research on Cancer.
The researchers, who examined colorectal cancer data from 1983-1987 through 1998-2002, found incidence rates for both males and females increased for 27 of 51 cancer registries. The increases were more prominent in men, and some were dramatic.
In Slovenia, for example, colorectal cancer incidence increased 70% among men and 28% among women. In Miyagi, Japan, rates rose 92% among men and 47% among women.
In the United States, colorectal cancer incidence rates declined in both males and females.
The increase in other countries likely reflects the adoption of Western behaviors and lifestyles. These include obesity, physical inactivity, smoking, heavy alcohol consumption, a diet high in red or processed meats, and inadequate consumption of fruits and vegetables.
The male colorectal cancer incidence rates in the Czech Republic, Slovakia, and Japan not only exceeded the peak incidence observed in the U.S. and other long-standing developed countries, but continue to increase.
Umar and Greenwald in a news release call the rising rates "alarming" and say they point "toward a failed early detection and prevention strategy as well as failure to address lifestyle and dietary challenges of urbanization that affect most of the globe."
Screening procedures for colorectal cancer such as colonoscopy has contributed to the decrease in incidence rates among males and females in the U.S., the study says.
Japan's problem, in essence, is that its people "have moved to California" in their behaviors and habits and adopted unhealthy diets and lifestyles, Jemal tells WebMD. The same is true in other nations undergoing transformations as their economies become more developed.
"This is very alarming," Jemal says.
SOURCES: News release, American Cancer Society, Atlanta. Center, M. Cancer Epidemiology Biomarkers and Prevention, June 2009; vol 18: pp 1688-1894. Editorial: Umar, A. and Greenwald, P. Cancer Epidemiology Biomarkers and Prevention, June 2009; vol 18: pp 1672-1673. Ahmedin Jemal, PhD, American Cancer Society, Atlanta.
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