Gen Z and Millennials: Do you know the signs of early-onset colorectal cancer?

By Sharon Doering-Domanus

The incidence of colorectal cancer in people ages 20-49 has increased alarmingly over the past three decades in the U.S. and other high-income countries. Colon and rectal cancers are highly treatable if caught early but are more challenging to treat in advanced stages.

Unfortunately, many cases of colorectal cancer in young adults are diagnosed when they have already progressed to an advanced stage. “A lack of awareness about early-onset disease and its symptoms can contribute to a delayed diagnosis,” explains Frank Sinicrope, M.D., a Mayo Clinic gastroenterologist and oncologist. Another contributing factor is that young adults are less likely to have a primary health care professional.

Here's what Dr. Sinicrope wants adults younger than 45 to know about colorectal cancer:

Colorectal cancer symptoms should never be ignored

Approximately 10% of colorectal cancers are diagnosed in people younger than 50. Young people should be aware of the warning signs. Talk to a health care professional if you have any symptoms associated with early-onset colorectal cancer, including:

• Blood in your stool or rectal bleeding
• Dark-colored, tarry stool
• Regular abdominal pain or bloating
• A change in your bowel habits or the consistency of your stool

Early-onset colorectal cancer differs from later-onset disease

Young adults with colorectal cancer typically have more advanced disease at diagnosis than those over 50. "Studies suggest patients with early-onset colorectal cancer have had a longer duration of symptoms and a longer delay in diagnosis than those with later-onset disease,” Dr. Sinicrope says.

Delayed diagnoses may be responsible for the rise in colorectal cancer deaths over the past decade among young adults. While the risk of early-onset colorectal cancer remains low, it is a leading cause of cancer death for people ages 20-49.

There may also be biological differences between early-onset and later-onset colorectal cancer. Early-onset cancers are most commonly detected in the rectum and left colon, and there has been an increase in the incidence of later-onset cancers in the right colon.

Health care professionals don’t know what’s causing the increase in colorectal cancer rates in young adults. Research suggests it may be related to risk factors such as a diet containing more processed foods, red meat, and sugar-sweetened beverages; obesity, and an inflammatory gut environment.

If you have a family history, start screening before age 45

The U.S. Preventive Services Task Force recommends that everyone begin colorectal cancer screening at age 45. But approximately half of people with early-onset colorectal cancer are diagnosed before age 45.  Dr. Sinicrope recommends taking an individualized approach to screening based on your risk factors and family history.

“Patients with a parent or sibling diagnosed with colorectal cancer or advanced polyps before age 60 should begin screening at age 40,” says Dr. Sinicrope. If your family member had an early-onset diagnosis, you should start screening 10 years earlier than their age at diagnosis.  

Dr. Sinicrope says about 25% of people ages 40 to 49 with early-onset colorectal cancer have a family history. “If an individualized approach had been applied to these patients, they would have undergone earlier screening, making an earlier diagnosis possible,” he says.

Most health care professionals recommend screening with colonoscopy. During this procedure, doctors identify and remove abnormal growths, called polyps, that form on the inner wall of the colon or rectum. Most polyps are noncancerous, but some can become cancerous over time.

If you're hesitant to get a colonoscopy, talk to your health care professional about less invasive screening options, including stool-based screening. “The best screening test is the one the patient will comply with,” says Dr. Sinicrope.

Don’t assume you’re too young to have colorectal cancer

Most early-onset colorectal cancers are not due to a known genetic syndrome or family history, cautions Dr. Sinicrope. If you're having symptoms related to colorectal cancer, it's critical to talk to a health care professional. And if you have a condition that increases colorectal cancer risk, such as ulcerative colitis or Crohn's disease, consider early screening.

If you’re in your 20s, 30s, or 40s and have blood in your stool, don’t assume it’s from a benign condition. Colorectal cancer needs to be considered and ruled out.

Learn more

Learn more about colon and rectal cancer and find a colorectal cancer clinical trial at Mayo Clinic.

Join the Colorectal Cancer Support Group on Mayo Clinic Connect.

Also, read these articles:

• "Polyps: Colon cancer culprits"
• "What to know when colorectal cancer runs in the family"
• "Younger than 50? Don’t rule out colorectal cancer"
• "What you should know about genetics, colorectal cancer"