Early-onset colon cancer: symptoms, risk factors, and when to get screened

Colon cancer has long been thought of as a disease that affects older adults. But that’s changing.

“We certainly know that colon cancer is one of the fastest growing or fastest rising incidences of cancer in the population under the age of 50,” says Dr. Noelle Bertelson, a colorectal surgeon with Intermountain Health.

Even more concerning, she explains, patients under age 45 are often “presenting with very advanced cancers.”

That shift is exactly why screening guidelines were lowered in recent years. Today, average-risk adults are advised to begin screening at age 45. But for younger adults who haven’t yet reached that milestone, awareness is just as critical.

What is early-onset colon cancer?

Early-onset colon cancer refers to colorectal cancer diagnosed in adults under age 50. 

Colon cancer usually develops slowly. “Colon cancer is essentially a slow disease process that starts typically for most patients as polyps,” Dr. Bertelson explains.

Polyps are small growths in the colon made up of disorganized cells. Over time, some polyps can grow, change, and eventually become cancerous. That process often takes years – which is exactly why screening is so powerful.

“That’s why it’s so important to be screened,” she says.

When polyps are found early, they can often be removed before they ever turn into cancer. That’s also why colon cancer is considered one of the most preventable cancers.

But prevention only works when people get checked.

Why are more young adults getting diagnosed with colon cancer?

Researchers do not yet have a single clear answer.

“We don’t really know why,” Dr. Bertelson says.

Experts suspect a mix of environmental factors, diet, lifestyle, and genetics may be contributing. About 20% of younger patients diagnosed with colon cancer have a genetic syndrome that predisposes them to cancer. But that means roughly 80% do not.

In other words, most younger adults being diagnosed have no obvious warning sign in their family history.

That unpredictability makes symptom awareness even more important.

Colon cancer symptoms in younger adults

Because routine screening typically begins at age 45 for average-risk adults, many people under that age won’t be screened unless something feels wrong.

Dr. Bertelson urges younger adults to pay attention to changes that are new or different for them. These can include:

• Rectal bleeding
• New abdominal pain
• Changes in bowel habits
• Ongoing constipation or diarrhea
• Unexplained weight loss
• Persistent fatigue

“If they have bleeding, if they’re having new onset abdominal pain or changes in their bowel habits or anything that just seems new or different for them, they should go into their primary care doctor and get things checked out,” she says.

Too often, younger adults assume symptoms are hemorrhoids, stress, diet changes, or something minor. Sometimes that’s true. But colon cancer can look similar in its early stages.

When in doubt, get evaluated.

Be your own advocate if you’re experiencing colon cancer symptoms

Talking about bowel habits isn’t exactly dinner table conversation. And younger adults may feel dismissed if they bring up concerns about colon cancer. 

That’s why Dr. Bertelson encourages patients to speak up.

“You do need to be your own advocate sometimes,” she says.

If something feels off and you’re worried, say so. Ask direct questions. Request further testing if symptoms persist. Most providers welcome those conversations and want to help you get clarity.

Colon cancer is much more treatable when caught early. Delaying evaluation because of embarrassment or fear can allow the disease to progress.

When should you get screened for colon cancer?

For average-risk adults, screening now begins at age 45. That recommendation changed in response to rising cases in younger populations.

“If you’ve hit that age 45, really just get in and get screened,” Dr. Bertelson says. “It’s so important and it’s a lifesaver.”

Colonoscopy remains the gold standard because it both detects and prevents cancer.

During a colonoscopy, doctors can remove polyps before they become cancerous. The procedure typically takes about 20 minutes, and most patients are asleep for it.

For those who aren’t ready for a colonoscopy, at-home options like FIT testing (done yearly) or stool DNA testing (every five years) are available. However, a positive result from those tests requires a follow-up colonoscopy.

While colonoscopy is the most comprehensive option, Dr. Bertelson emphasizes that “any screening is better than no screening.”

If you’re diagnosed with colon cancer, there is hope

Hearing the word “cancer” can be frightening at any age. But colon cancer is one of the most common cancers in the United States, which means physicians have extensive experience treating it – and most colon cancers are treatable when caught early.

Surgical techniques have advanced significantly. Many patients spend just a day or two in the hospital after surgery. New therapies, including immunotherapy, continue to expand treatment options.

“There is so much research and technical advancements,” she says. “Our screening modalities are getting better and better. Patient tolerance is getting better and better.”

Colon cancer is preventable, treatable, and beatable at Intermountain Health

If you are under 45, know the symptoms and speak up if something changes.

If you are 45 or older, schedule your colon cancer screening.

Colon cancer is one of the few cancers we can often prevent. But prevention only works when screening happens.

At Intermountain Health, our colorectal specialists and gastroenterology teams are committed to early detection, prevention, and advanced treatment. Whether you need your first colonoscopy, want to explore at-home screening options, or have symptoms you want evaluated, we are here to help. You can visit our Colon Cancer Screening page to learn more about your options.