A Trusted Friend in a Complicated World

9 Colorectal Cancer Risk Factors You Can Control—and 7 You Can’t

While colon cancer is the second leading cause of cancer deaths in the United States, in many cases it is preventable—as long as you know how to reduce your risk.

1 / 16
Bathroom scales and yoga mat on wooden background, top view. Weight loss concept
New Africa/Shutterstock

You can control obesity

More than two in three American adults are overweight or obese, according to statistics from the National Institute of Diabetes and Digestive and Kidney Diseases. Along with heart disease and diabetes, these conditions are directly linked to an increased risk of colon cancer. “Studies have shown that as countries have more Western diets, their rates of colon cancer increase,” says Heather Yeo, MD, colon and rectal surgeon at Weill Cornell Medicine. While obesity can be hard to control, it is possible with the help of medical and surgical intervention to manage weight. Learn about these other 15 things oncologists do to prevent cancer.

2 / 16
family photos

You can’t control your family history

Family history and genetics account for about 15 percent of patients with colon cancer, according to Anton Bilchik, MD, PhD, professor of surgery and chief of gastrointestinal research at John Wayne Cancer Institute at Providence Saint John’s Health Center in Santa Monica, California. For this reason, any individual who is diagnosed with colon cancer under age 50 should undergo a workup for the presence of these genetic mutations. “These tests are simple to perform and easily available by performing a blood test,” Dr. Bilchik explains. “If the gene is present, then closer surveillance is needed for family members.”

3 / 16
Healthy Green food Clean eating selection Protein source for vegetarians: avocado, asparagus, apple, broccoli, spinach, spirulina, green peas on gray concrete background
Lisovskaya Natalia/Shutterstock

You can control your fiber intake

Diets high in fiber from fruits, vegetables, whole grains, nuts, and legumes can be protective against colorectal cancer. “Soluble fiber, which is fermented by gut bacteria, leads to the production of short-chain fatty acids like butyrate, which have anti-cancer properties in the colon,” explains Shilpa Ravella, MD, gastroenterologist and assistant professor of medicine at Columbia University Medical Center. She recommends including as much fiber in the diet from whole plant foods as possible. Find out which 13 foods can help cleanse your colon.

4 / 16
generation women family
George Rudy/Shutterstock

You can’t control a family history of colorectal polyps

A third of patients diagnosed with colorectal cancer have a family member with a history of colorectal cancer or colorectal polyps, according to Samir R. Shah, MD, colorectal surgeon at Lexington Medical Center in West Columbia, South Carolina. “Generally you want to start the screening process ten years prior to the youngest age of the affected family member,” he says. “If you’ve ever had polyps, your risk of colorectal cancer is higher than an individual without any history of polyps, so it is crucial to continue surveillance with regularly scheduled colonoscopies or accepted forms of screening.” Here are more reasons to be screened for colorectal cancer.

5 / 16
Fork with pieces of delicious barbecued meat on gray background, top view
New Africa/Shutterstock

You can control the red and processed meat in your diet

Research links a diet high in red and processed meats to an increased risk of colorectal cancer. “Heme iron, nitrates, nitrites, and other potential carcinogens found in meats that have been pan-fried, barbecued, seared, and cooked at high temperatures—including beef jerky, corn beef, ham, bacon, sausage, and other cured meats—are the cause,” says Cedrek McFadden, MD, colorectal surgeon and clinical assistant professor of surgery at the University of South Carolina School of Medicine Greenville. “It should be noted, however, that this absolute risk of consumption of red and processed meat is small and only occurs with the daily consumption of these foods.” In other words, most experts say you should limit your servings to one to two a week. Watch out for these other 12 foods cancer doctors try not to eat.

6 / 16
Hands of an old woman with a cane

You can’t control your age

Like most diseases, colorectal cancer risk increases as you age. The likelihood of a diagnosis increases after the age of 40 and rises sharply after age 50, says Eyal Meiri, MD, interim chief of medical oncology at Cancer Treatment Centers of America in Atlanta. “The concern of late, however, has been the increasing incidence of colorectal cancer in young adults,” he says. This finding has led to the American Cancer Society’s change in recommendations for colorectal cancer screening at 45 instead of 50.

7 / 16
I am Kulz/Shutterstock

You can control whether or not you smoke

Cigarette smoking is responsible for a myriad of illnesses, many of which are fatal, and colorectal cancer is one of them. In fact, research shows that the risk of colon cancer jumps 19 percent in women smokers and 8 percent in male smokers. “Some studies show even a few cigarettes a day can increase your risk for colon cancer, let alone other malignancies, so just don’t start,” says Dr. Shah.

8 / 16
toilet paper roll
New Africa/Shutterstock

You can’t control a history of inflammatory bowel disease

“Those suffering from inflammatory bowel disease (IBD), including Crohn’s disease or ulcerative colitis, tend to have chronic inflammation in their colon and intestines, which can increase the risk of colorectal cancer,” says Dr. Ravella. “The increase in the risk of colon cancer begins several years after the initial diagnosis and is especially pronounced in patients with large areas of the colon affected, the longest disease duration, and in those with active inflammation.” For this reason, all patients with IBD should talk to their gastroenterologists about when to start screening for colon cancer. Plus, don’t miss these 50 rampant cancer myths you need to stop believing.

9 / 16
wine bottle

You can control how much alcohol you drink (and how often)

Too much alcohol is another vice that can have severe health consequences including colorectal cancer.  One analysis of studies found that heavy drinkers raised their colorectal cancer risk by 37 percent compared to non-drinkers, and even light drinkers had a 7 percent increase in risk. “Particularly, alcohol use is associated with younger onset of colorectal cancer that is usually found in the left side of the colon,” says Dr. Meiri.

10 / 16

You can control how often you eat garlic and onions

Allium, a substance found in garlic, onions, shallots, chives, scallions, and leeks seems to lower the risk of colorectal cancer, likely by defusing carcinogens and interrupting blood supply to tumors. Research published in the Asia-Pacific Journal of Clinical Oncology matched 833 people with the cancer to the same number of healthy people of about the same age, sex, and other demographics. After comparing diets, the researchers found that people who ate plenty of allium-containing vegetables had 79 percent lower risk of colorectal cancer, compared to those whose diets were largely allium-free. “It is worth noting that in our research, there seems to be a trend: The greater the amount of allium vegetables, the better the protection,” said senior author Dr. Zhi Li of the First Hospital of China Medical University in a news release. Load up on these other 30 foods proven to help prevent cancer.

11 / 16
african hands folded

You can’t control your race and ethnicity

“African Americans have the highest risk of developing and dying from colorectal cancer, with a 20 percent higher mortality, as well as a higher stage of disease at presentation,” says Dr. McFadden. “I suspect these differences are related to genetics or more aggressive tumor biology and/or lower rates of screening.” Additionally, he points out that with many doctors believing this is a disease of “older white men,” many African Americans may not learn preventive strategies. The recommendation for African Americans is to begin screening colonoscopies at 45 years of age. Make sure you know these other 13 signs of cancer men are likely to ignore.

12 / 16
Composition with dumbbells and fitness accessories on floor
New Africa/Shutterstock

You can control your physical activity level

The U.S. Department of Health and Human Services recommends that adults get at least 150 minutes of moderate physical activity a week—a goal that too few of us reach on a consistent basis. As Dr. McFadden points out, people who are more physically active lower their risk of colorectal cancer and their chances of developing breast cancer, heart attacks, diabetes, and stroke. “This increase in physical activity tends to also reduce obesity, which also can reduce the risk of colorectal cancer,” he adds.

13 / 16
Medical scalpel and vial for injection in hands wearing blue gloves
Oleg Troino/Shutterstock

You can’t control your transplant status

According to Dr. Ravella, patients who have received an organ transplant, such as a kidney, can have a higher risk of developing colorectal cancer because of the risks that come with long-term use of drugs that suppress immunity. For this reason, she recommends that such patients discuss more frequent screening with their gastroenterologist.

14 / 16
white pills

You can control your aspirin use

In recent years, the U.S. Preventive Services Task Force has found the practice of taking daily aspirin can reduce the risk of colorectal cancer by 40 percent in high-risk patients. However, Dr. Yeo points out that aspirin can increase the risk of gastric bleeding—yet patients need to use it consistently for long periods of time to show improvement. Discuss your colorectal cancer risk and potential side effects of aspirin with your doctor before taking it routinely. You should also reconsider your habits if you’ve been doing these things you think prevent cancer—but don’t.

15 / 16
IV bag hospital cancer

You can’t control exposure to abdominal radiation as a child

Childhood cancer survivors who got radiation treatment can be at increased risk of colorectal cancer, notes Dr. McFadden. “An increase in risk is also seen in patients who have had radiation for treatment of prostate cancer or cervical cancer,” he says. “This finding leads to recommendations to begin screening for colorectal cancer … at a young age in these patients (either ten years after radiation or at the age of 35).”

16 / 16
Endoscopy. Doctor holding endoscope before colonoscopy
Doro Guzenda/Shutterstock

You can control getting screened

Experts believe that screening is one of the most important things people can do to reduce their colon cancer risk. “There are a number of screening tests, including colonoscopy and stool-based tests, that are available,” says Sonia Kupfer, MD, internist and gastroenterologist at the University of Chicago Medical Center. The American Cancer Society recommends that average-risk individuals start regular screening at age 45, and those at an increased risk start before 45. If you’re not sure where you fall, it’s best to discuss your risk with your doctor. In the meantime, start these 12 everyday habits that can help prevent colon cancer.

Jenn Sinrich
Jenn Sinrich is a freelance writer and editor with a passion for health, wellness and all things beauty. She has written for Women's Health, Shape, Self, Men's Health, Glamour and Healthline. Jenn holds a degree in journalism from Northeastern University, and she currently resides outside of Boston with her husband and two children. When she's not working, you can find her exercising, trying out new healthy recipes or exploring the city with her family.