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 common cancer in both men and women in the U.S. Colorectal includes cancer of the colon and rectum.

Overall, the lifetime risk of developing colon cancer is about 1 in 23 (4.4 percent) for men and 1 in 26 (4.1 percent) for women.

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The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has decreased in both men and women for several decades. One reason is the increased detection of colorectal polyps through screening. Treatment has also improved.

Why is colon cancer common?

One reason colon cancer is so common is the aging of America. Colon cancer occurs more frequently in people over 50. With the 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, MD, former director of the West Virginia University Cancer Institute.

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. 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 among the top 10 most obese nations in the world. About 42 percent of U.S. adults are obese. The rate has risen steadily for decades.

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 increases. Smoking is well-known cause of lung cancer but is also linked to several other cancers. Cigarette smoking is the leading cause of preventable disease and death in the United States.

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.

While colon cancer rates have fallen since the mid-1980s, they have risen in people under the age of 50.

"The 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. It could be that people are getting screened for colon cancer earlier. Some evidence backs that claim. While the rate of new cases of colon cancer in people under 50 has been rising since the mid-90s, the death rate has remained flat, which may be the more important figure.

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