Why Colorectal Cancer is Rising in Young Adults: Q&A with an Emory Winship Colorectal Surgeon

Colorectal cancer is now the leading cause of cancer death in adults under 50 in the U.S., making early screenings even more important. Emory Winship colorectal surgeon Patrick Sullivan, MD, explains what patients need to know about cancers of the colon and rectum, symptoms not to ignore, factors that likely play a role in early onset and why colonoscopies are key.

What is colorectal cancer?

Think of your digestive tract as a long tube: Food travels down the esophagus to the stomach, then moves through the small intestine, where most digestion happens. It then enters the colon, a segment about 5 feet long that absorbs water and salt and stores stool before a bowel movement. The rectum is the last part of the colon. Colorectal cancers are cancers of the colon and rectum.

What symptoms should I never ignore?

Blood in the stool or rectal bleeding. Bleeding is never normal until proven otherwise. Other symptoms include crampy abdominal pain, a change in bowel habits (new constipation or diarrhea), iron-deficiency anemia, and unintentional weight loss. Abdominal pain can happen if a tumor narrows the colon. If something changes and doesn’t go back to normal, get evaluated by your primary care physician. 

Is colorectal cancer really increasing in younger adults?

• Yes, and it’s concerning. “Early-onset” colorectal cancer is defined as cancer diagnosed before age 50. Here’s what we know:
• Rates in adults under 50 have been rising about 2% per year since the 1990s.
• In people under 40, rates are rising even faster — about 3–4% per year.
• Early-onset cases now account for about 15% of all colorectal cancers.
• Colorectal cancer is now the leading cause of cancer death in men under 50 and the second leading cause of cancer death in women under 50, after breast cancer.
• This is not just happening in the U.S. It’s a global trend, especially in high-income countries. At the same time, however, rates in older adults are declining, largely due to improved screening.

Why the rise in early onset colorectal cancer?

There is no single cause. But several factors that likely play a role are:

• Genetics - Your genes are the most important risk factor. About half of colorectal cancers have an inherited component. Some people are born with genetic changes that increase their risk. In those cases, lifestyle or environmental exposures may “push” the disease to develop earlier.
• Obesity - Obesity (body mass index of over 30) is one of the strongest risk factors for colorectal cancer. Nearly 40% of U.S. adults are considered obese. Excess body fat changes hormone levels and increases inflammation, and both are linked to cancer risk.
• Diet - The typical Western diet plays a major role. Red meat and processed meats (like bacon, hot dogs and deli meats) increase risk, as do other highly processed foods, which often contain preservatives, additives and stabilizers, as well as sugary drinks. Smoking and drinking alcohol also increase risk.
• Sedentary lifestyle - Regular exercise lowers risk. Spending long hours sitting, especially more than 14 hours per day, is linked to a higher risk.
• Metabolic disorders - Conditions like Type 2 diabetes, high blood pressure and metabolic syndrome are associated with increased risk.
• Environmental exposures - Researchers are investigating environmental factors, including microplastics, heavy metals, pesticides and herbicides, as well as early and frequent antibiotic use, which may alter the microbiome (gut bacteria).

How is Emory Winship advancing understanding of why colorectal cancer is rising among younger people? 

At Winship, our main research areas focused on early onset colorectal cancer include:

• Studying how rates of the disease have changed over time and how it affects different groups of people
• Identifying possible causes and risk factors, including genetics, lifestyle habits, and environmental exposures
• Using molecular profiling to better understand the unique biology of colorectal cancer that develops at a younger age
• Exploring whether changes in the gut microbiome may play a role in the development of the disease 

Is a colonoscopy still the gold standard?

Yes—colonoscopies are the best way to detect both colon cancer and pre-cancerous polyps. A colonoscopy looks at the entire colon, can detect cancer, and can find and remove polyps before they turn into cancer. Most colorectal cancers develop slowly: It often takes five to 10 years for a polyp to form and another five to 10 years for that polyp to become cancer. That’s why screening works.

What are polyps, and if they are found, does it mean that the patient will eventually get cancer?

Polyps are growths inside the colon. Some are precancerous, but not all polyps become cancer. The risk depends on their size, number and microscopic features. If polyps are found and removed, follow-up colonoscopies may be done more frequently. Removing polyps is how we prevent cancer.

What does early detection change for patients in terms of treatment options and outcomes? 

Early detection can prevent colorectal cancer entirely by removing precancerous polyps during colonoscopy. When cancer is found early, treatment is often less invasive and may involve curative surgery alone, sometimes avoiding chemotherapy. Survival rates are much higher for localized, contained disease (91% five-year survival) compared to advanced cancer (14%), and patients diagnosed through screenings have significantly better outcomes than those diagnosed after symptoms appear.

What about other screening tests?

There are multiple screening tests. Options include:

• FIT test (fecal immunochemical test) – done yearly; detects blood.
• Stool DNA test (Cologuard) – detects abnormal DNA and blood.
• CT colonography – a virtual colonoscopy.
• Flexible sigmoidoscopy – looks at part of the colon.

If any of these tests are positive, you will still need a colonoscopy. The most important message is simple: get screened. If you’re afraid of a colonoscopy, choose another approved method. But don’t skip screening altogether.