What People Under 50 Need to Know About Their Colon Cancer Risk

Health Writer
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Lately, it’s been good news/bad news on the colorectal-cancer front. Let’s share the good news first: The rate of this cancer has been dropping since the 1980s, mostly due to colonoscopies and other screening tests for people 50+ that allow doctors to spot and remove polyps that can turn malignant. The bad news? Rates have been climbing among Millennials (roughly 23 to 38 years old in 2019) and Gen X-ers (about 39 to 54). And not just by a little. Compared to 29-year-old Baby Boomers in 1979, adults that age today have twice the risk of colon cancer and quadruple the risk of rectal cancer.


The Role of Obesity

Experts aren’t sure exactly what’s behind the rise in colorectal cancer in younger people, but it’s likely that increasing obesity, unhealthy diets, and physical inactivity all play a role. Rates of obesity and overweight more than doubled in children and teens between 1980 and 2014, from 15% to over 33%—an appreciably bigger increase than in adults aged 20 to 74. “People who are overweight are more likely to have conditions that cause chronic low-level inflammation,” says Rebecca Siegel, strategic director of surveillance information services for the American Cancer Society. “An example is gastroesophageal reflux, which causes inflammation of the esophagus. Chronic inflammation can cause DNA damage over time that leads to uncontrolled cell growth and cancer.” Indeed, colorectal cancer isn’t the only kind of cancer on the rise in younger people. So are five other cancers known to be related to obesity, including gallbladder, kidney, and pancreatic cancers.


The Diabetes Connection

Excess weight delivers a double whammy. Not only does it cause inflammation that encourages cells to turn cancerous, it also leads to other diseases that make cancer more likely to develop. For instance, studies suggest that type 2 diabetes raises the risk of colorectal cancer. If so, that doesn’t bode well for the future: Type 2 diabetes used to be called adult-onset diabetes because it was so rare in children and teens, but it’s been rapidly increasing in younger Americans since the 1980s.


How Diet Helps–and Hurts

Maintaining a healthy weight is one way to reduce the risk of colorectal cancer. What you eat—or don’t eat—also affects your likelihood of developing colorectal cancer. Consuming plenty of fruits, vegetables, and whole grains is protective, while a meat-heavy diet raises risk. Processed meats like hot dogs, ham, and bacon are especially problematic. World Health Organization (WHO) experts analyzed more than 800 studies and concluded that eating about four strips of bacon a day, or an equivalent amount of other processed meat, raises the risk of colorectal cancer by 18%. Unfortunately, researchers say, the typical diet among young people has been getting worse over the past few decades: fewer fruits, veggies, and whole grains; more sodium and sugar-sweetened drinks.


A Surprisingly Sneaky Danger

The most obvious culprits – like excess weight and a sedentary lifestyle – may not fully explain the increase in colorectal cancer at younger ages. “There may be other factors at play,” says ACS researcher Rebecca Siegel. One possibility: the overuse of antibiotics, which can knock out good-for-you bacteria as well as disease-causing varieties in the digestive system. Some studies suggest that our natural load of bacteria, part of what’s called the microbiome, plays a role in keeping us healthy. “Information about how the gut microbiome influences health in general, and cancer in particular, is still in its infancy,” Siegel says, “but it would make sense that something that changes the microbiome, like antibiotics, might be important.” In some states, enough antibiotics are prescribed each year to dose every inhabitant and still have some left over. Don’t give your doctor the stink-eye when he or she doesn’t prescribe them -- remember: Antibiotics don’t work against colds or other viruses!

A Little Exercise Goes a Long Way

It also helps to be active–getting regular exercise cuts the risk of colon cancer by 20% or more. It’s not clear exactly why that is, but according to the National Cancer Institute, working out reduces chronic inflammation, cuts levels of insulin and certain chemicals called growth factors, and changes the metabolism of bile acids, among other things, all of which may play a role. You don’t have to go crazy. Activities as simple as brisk walking definitely count; more intense exercise seems even better. Aim for half an hour of exercise most days of the week and ramp up if you’re able. It also makes a difference to build activity into your day–for instance, taking the stairs instead of the escalator and parking at the far end of the lot if you drive to the store.

More Incentive to Quit

Here’s an unsurprising tip: Don’t smoke. Smoking doesn’t just raise your risk of lung cancer and heart disease; it’s also linked to at least 11 other cancers, including colorectal cancer. (More than 16% of Millennials smoke, according to the Centers for Disease Control and Prevention—a higher percentage than in older or younger generations.) Alcohol also raises your risk of colorectal cancer, possibly because bacteria that normally live in the colon and rectum turn it into a chemical called acetaldehyde. In lab animals, acetaldehyde can cause cancer–and the same may be true in humans, says the American Cancer Society. If you drink, keep it moderate. (In a 2017 survey by the federal government, about 43% of younger Millennials reported occasional binge-drinking—meaning five or more drinks on a single occasion for men and four or more for women.)


Screen, Screen, Screen

Tell your doctor about any family history of colorectal cancer. The United States Preventive Services Task Force—a respected organization that issues guidelines on screening tests — recommends that people at average risk for the cancer start being screened at age 50. The ACS recently lowered their recommended starting age to 45. But if a close family member was diagnosed with colorectal cancer before age 60, or if two family members were diagnosed at any age, start screening at age 40, or when you’re 10 years younger than the earliest diagnosis—whichever comes first. During colonoscopy, a doctor looks for and removes polyps, the small growths in the colon that, if left alone, can develop into cancer. But if the thought of the prep (which has gotten easier in recent years) gives you the willies, there are other effective tests, like annual fecal blood screening. The best test? The one that gets done, researchers say.


Take Symptoms Seriously

If you have a change in your bowel habits that lasts for more than a month or so—constipation, diarrhea, a different consistency—tell your doctor. Ditto if you have rectal bleeding or blood in your stool, or persistent cramps, gas, or abdominal pain or discomfort. Younger adults who develop colorectal cancer are 58% more likely than older people to have late-stage disease by the time they’re diagnosed, probably because the problem isn’t on their radar–or their doctor’s, either. “Young people with these symptoms usually don’t have cancer, but sometimes they do,” Siegel says. “And survival is much more likely with earlier diagnosis.”


Persistence is Key

Trust your body. In a survey of people diagnosed with colorectal cancer before age 50, 67% saw at least two doctors before their cancer was found, and some saw as many as four, says Ronit Yardin, Ph.D., director of medical affairs at the Colorectal Cancer Alliance. Because cancer isn’t top-of-mind when a younger patient comes in, a doctor might not recommend tests that could identify colorectal cancer at first, focusing instead on other possible explanations, from hemorrhoids to inflammatory bowel disease. But if your symptoms are persistent, you need to be persistent too, she says.