Genetic Conditions Inherited physical problems such as Lynch syndrome and familial adenomatous polyposis (which can produce hundreds of polyps in the colon) increase the chances of developing colorectal cancer, especially at a young age.
“Younger adults with colon cancer are more likely to have an inherited syndrome,” says Kelley Chan, MD, a clinical scholar with ACS Cancer Programs, and resident at Loyola University Medical Center in Chicago.
The Global Colon Cancer Association estimates that 16 to 25 percent of early-onset cases are related to a genetic syndrome, whereas only up to 10 percent of regular colorectal cases are related to genetics.
Racial and Ethnic Background American Indian and Alaska Native people have the highest rates of colorectal cancer in the United States, followed by African American men and women. Jews of Eastern European descent (Ashkenazi Jews) also have a high risk compared to other ethnic groups; about 6 to 8 percent carry a specific gene mutation that increases their risk of developing colorectal cancer by 1.5 to 2 times.
Other Health-Related Issues Certain health-related conditions may contribute to colorectal cancer risk, including a family history of the disease, a personal history of radiation to the abdomen or pelvis area, a personal history of inflammatory bowel disease (Crohn’s or ulcerative colitis), and having had the gallbladder removed (cholecystectomy).
Toxins in the Environment Researchers are studying whether exposure to chemicals may play a role in colorectal cancer. Chemical exposures (from air and water pollution, chemicals in soil and food, and pesticide use) may damage the DNA of intestinal cells leading to cancer-causing mutations.
Modifiable Risk Factors
According to one study, one-third to one-half of all early-onset colorectal cancer cases are attributable to modifiable risk factors, including:
Obesity A review of more than 100 scientific papers found that half of younger adults with colorectal cancer were overweight and 17 percent were obese. Excess fat has been linked to inflammation, which may raise the likelihood of developing cancer. Obesity is also connected to insulin resistance and diabetes, increased production of the hormone leptin, and gut hormone imbalance — all factors tied to greater cancer risk.
Unhealthy Diet Colorectal cancer has been linked to the consumption of red meats (such as beef, pork, lamb, or liver) and processed meats (like hot dogs and some lunch meats). Research has also found that sugar-sweetened drinks may be a culprit.
Lack of Exercise Research has shown that physical inactivity and sedentary behavior are well-established risk factors for colorectal cancer. Insufficient exercise may contribute to weight gain, insulin resistance, and inflammation.
Smoking A study involving more than 700 adults under the age of 55 with colorectal cancer found that former smokers had a 139 percent higher risk of developing colorectal cancer compared with nonsmokers in the same age group. For current smokers, that risk was 150 percent greater.
Alcohol Use Moderate to heavy alcohol consumption is a known risk factor for colorectal cancer. Alcohol consumption can damage the intestinal lining, allowing bacteria and toxins to enter other tissue in the body. A scientific investigation looking at more than 8,000 colorectal cancer patients between ages 20 and 49 found that the risk increased in relation to how much a person drank. Compared with nondrinkers, those who had one to two drinks weekly had a 7 percent higher risk. For those having three to four drinks per week, the risk was 14 percent higher, while five drinks or more equaled a 27 percent greater risk.
