A new study finds colorectal cancer incidence rates for both males and females increased in 27 of 51 countries worldwide between 1983 and 2002, and points to increasing Westernization as being a likely culprit. The rise was seen primarily in economically transitioning countries including Eastern European countries, most parts of Asia, and some countries of South America.
Colorectal cancer is the fourth most common cancer in men and the third most common cancer in women worldwide. Previous studies have reported rapid increases in colorectal cancer incidence rates in economically transitioning countries in many parts of the world, likely reflecting changing dietary and physical activity patterns. However, those studies used old data and examined regional or country-specific trends. The new study, led by American Cancer Society epidemiologist Melissa Center, MPH, reviewed colorectal cancer incidence data from 51 cancer registries worldwide with long-term incidence data from the Cancer Incidence in Five Continents (CI5) databases created by the International Agency for Research on Cancer (IARC). Researchers analyzed the change in incidence rates over the past 20 years; 1983-87 through 1998-2002.
They found colorectal cancer incidence rates for both males and females increased for 27 of 51 cancer registries considered in the analysis between 1983-87 and 1998-2002. The increases were more prominent for men than for women. Some of the increases were dramatic. For example, in Slovenia, colorectal cancer incidence increased 70 percent among men and 28 percent among women. In Miyagi, Japan, rates rose 92 percent among men and 47 percent among women.
The researchers also observed substantial regional and ethnic variations in colorectal cancer incidence trends within countries such as Japan, Israel, and Singapore. The United States was the only country where colorectal cancer incidence rates declined in both males and females.
The authors say the increase in colorectal cancer in economically transitioning countries may reflect the adoption of western lifestyles and behaviors. Many of the established and suspected modifiable risk factors for colorectal cancer, including obesity, physical inactivity, smoking, heavy alcohol consumption, a diet high in red or processed meats, and inadequate consumption of fruits and vegetables, are also factors associated with economic development or westernization. The authors say male colorectal cancer incidence rates in the Czech Republic, Slovakia, and Japan have not only exceeded the peak incidence observed in the United States and other long-standing developed nations, but continue to increase.
An accompanying editorial by Asad Umar and Peter Greenwald of the Division of Cancer Prevention of the National Cancer Institute calls the rising rates "alarming," saying "this increase points 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."
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