Why Is Colon Cancer So Common?

Your lifetime risk of developing colon cancer is over 4 percent for both men and women. Here’s why this colon cancer is so common.

Excluding skin cancers, colorectal cancer is the third most commonly diagnosed in both men and women in the U.S. Colorectal includes cancer of the colon and rectum.

Overall, the lifetime risk of developing colorectal cancer is about 1 in 21 (4.7 percent) for men and 1 in 23 (4.4 percent) for women.

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The death rate (the number of deaths per 100,000 people per year) from colorectal cancer, however has been dropping in both men and women for several decades. One reason is that colorectal polyps are being detected through screening more than ever. Treatment also has improved over the decades.

Why is colon cancer common?

One reason colon cancer so common is the aging of America. Colon cancer occurs more frequently in people over 50. With the huge baby boomer wave growing older, more cases of colon cancer are inevitable.

Another reason, especially in the U.S., are high-fat, low-fiber diets that are heavy in red and processed meat, a known risk factor for the disease.

"Colon cancer is quite rare in Japan, although it's becoming more common as their diet becomes Westernized," says Richard Goldberg, the physician-in-chief and a professor of medicine at The Ohio State University Comprehensive Cancer Center.

First-generation Japanese immigrants who move to Hawaii notice an uptick in colon cancer rates, and "after a generation, the immigrants adopt the incidence of their adopted country," Goldberg said.

Individuals with a family history of colon cancer, especially if more than one relative has had the disease, are at increased risk. Also, two genetic syndromes, familial adenomatous polyposis and Lynch syndrome, have been associated with colon cancer.

Lifestyle risk factors for colon cancer

Several lifestyle-related risk factors have been linked to colon cancer. If you’re overweight or obese, your risk of developing and dying from colon cancer increases.

America is considered one of the top 10 most obese nations in the world. The total percentage of obese people in the U.S. is 32.8. That was a 13 percent increase between 2010 and 2014.

Also, if you’re not physically active, you have a greater chance of developing colon cancer.

If you have smoked for a long time, your risk goes up. Smoking is well-known cause of lung cancer but is linked to several other cancers, as well.

Cigarette smoking is the leading cause of preventable disease and death in the United States, accounting for more than 480,000 deaths every year, or 1 of every 5 deaths.

Likewise, colon cancer has been linked to heavy alcohol use. Limiting alcohol use to no more than two drinks a day for men and one drink a day for women could have many health benefits, including a lower risk of colorectal cancer, according to the American Cancer Society.

Oddly, while colon cancer rates have been falling dramatically since the mid-1980s, there has been an increase in the disease in those under 50 years of age.

"[T]he results do not provide any direct evidence about the role of specific exposures or interventions," the authors note in one study. Even so, the researchers say, because trends in the young "could be a bellwether of the future disease burden, our results are sobering. "

The reason for the uptick isn’t clear. It could be the rise in obesity, but no one really knows. Or it could be that people are getting screened for colon cancer earlier, which would explain the trend.

Some evidence backs that claim. While the rate of new cases of colon cancer in people under 50 have been rising since the mid-90s, the death rate has remained flat, which may be the more important figure.

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