- A new study found the proportion of people diagnosed with colon cancer who are under 50 years old rose from 10 per cent in 2004 to 12.2 per cent in 2015.
- The rates of bowel cancers in younger people have been rising for decades.
- While the cause of the increase is unclear, genetics, diet, and gut bacteria changes may be involved.
- It’s important for young people to make educated decisions about screening and understand the warning signs of colorectal cancer.
- Visit INSIDER’s homepage for more.
If you’re in your 20s, 30s, or 40s, bowel cancer may not be top of mind. But research indicating that you shouldn’t wait until your 50s or beyond to consider your risk continues to mount.
The latest study, published Tuesday in the journal Cancer, found that the proportion of patients under 50 who were diagnosed with colorectal cancer, which includes cancers of both the colon and the rectum, rose from 10% in 2004 to 12.2% in 2015, the most recent year data was available. Researchers looked at data from at the National Cancer Database registry, including the more than 1 million new cases of colorectal cancer diagnosed in total during that timeframe.
The study also found that younger adults tend to be diagnosed at more advanced stages of the disease, with 51.6% of those under 50 diagnosed with stages three or four, while only 40% of people over 50 were diagnosed at those later stages.
This is hardly the first time researchers have recognised the trend: Just last year, similar data came out of the American Cancer Society showing that rectal cancer rates for 20- to 49-year-olds nearly doubled between 1991 and 2014, INSIDER previously reported.
“Several studies have shown that the rates of colorectal cancer in younger adults have risen slowly in the US since the 1970s, but for practicing physicians, it feels like we are seeing more and more young people with colorectal cancer now than we were even 10 years ago,” study author Dr. Boone Goodgame of The University of Texas at Austin said in a statement released along with the current study.
Genetics, diet, and gut bacteria may be contributing to the increase
Experts aren’t sure what’s causing colon cancer more frequently in younger people, but it is clear there’s not only one cause.
Earlier research has shown that diets high in red and processed meats and low in fibre are linked to an increase risk of bowel cancers, and meat-heavy diets like paleo and keto aren’t helping, Tamara Duker Freuman, a registered dietitian who specialises in gastrointestinal issues, told INSIDER.
“So many of these low-carb diets are the textbook example of a colon-cancer promoting eating pattern, and the short-term weight-loss benefits may distract people from the potential long term risks associated from high meat, lower-fibre diets,” she said.
Obesity, too, is a risk factor for colorectal cancer, and those rates are rising alongside it. A 2017 study in the Journal of the National Cancer Institute discussing the changing disease rates noted that while young people who are developing these cancers tend to drink and smoke less than older generations, they have higher rates of obesity.
Other factors like access to health care resources and changes to gut bacteria (in part due to antibiotic use) may help explain the new data, too. A large study out of the UK identified a strong association between oral antibiotic use in the previous 10 years and colon cancer diagnosis.
Genetics also shouldn’t overlooked: “The number of colorectal cancer cases from inherited causes are much higher in younger individuals,” Dr. Chyke Doubeni at the University of Pennsylvania noted in a commentary accompanying the recent study.
Other risk factors for colon cancer at any age include alcohol and tobacco use; history of Type 2 diabetes and inflammatory bowel disease; and African-American heritage.
Age is also a major factor. While the current study rightfully raises alarm bells, you’re still a lot more likely to get colon cancer after age 50 than before, Dr. David Greenwald, a professor of medicine and gastroenterology at the Icahn School of Medicine at Mount Sinai, told INSIDER.
“The most important factors associated with an increased risk of colorectal cancer include advancing age and a genetic predisposition to colorectal cancer.”
Know the warning signs and screening options
Screening recommendations vary. The American Cancer Society recommends that average-risk adults who are 45 years old and older undergo regular screening, either with colonoscopy or a stool test. The U.S. Preventative Services Task Force, meanwhile, strongly recommends screenings beginning at age 50.
When you begin screening is a decision to make with a doctor, who can help weigh the risks and benefits based on your own risk factors.
If colorectal cancer runs in your family, it’s a good idea to be tested on the earlier end. If you have no risk factors, waiting may be preferable since screenings aren’t error-proof and can cause people who are healthy to undergo unnecessary tests and, in some cases, treatments with side effects of their own.
Screening aside, it’s important for young people especially to be aware of colorectal cancer symptoms, Greenwald said. “It is very clear that signs and symptoms that might indicate colorectal rectal cancer in those under 50, and particularly rectal bleeding, should be evaluated by a health care professional promptly and not dismissed as ‘only hemorrhoids’ or ‘normal,'” he said.
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