Colorectal cancer has long been associated with older adults, but a new study suggests that may be changing.
While incidence rates have fallen steadily among adults 65 and older, they are moving in the opposite direction for younger adults, according to a 2026 study from the American Cancer Society. The study found that incidence among adults ages 20 to 49 has increased by 3% annually since 2013, and that colorectal cancer is now the leading cause of cancer-related death in adults younger than 50.
Researchers are still working to understand exactly what is driving the rise, with the report citing possible factors such as obesity, diet, inactivity and changes in the gut microbiome. As scientists search for a definitive cause, local specialists say the best defense right now is early detection.
“I would say the most important message is to get screened as soon as you are eligible,” said Dr. Cristina Harnsberger, a colorectal surgeon with Sutter Health Greater Central Coast.
For average-risk adults, that generally means beginning colorectal cancer screening at age 45, after the American Cancer Society lowered the recommended starting age from 50 in 2018.
Harnsberger said that includes recognizing symptoms that should not be ignored, including rectal bleeding, changes in bowel habits, abdominal pain and unexplained weight loss.
The 2026 study also found that adults younger than 50 experience a 40% longer delay to diagnosis than older adults, often because symptoms are misdiagnosed as more common conditions. The report also noted that lower symptom awareness and health insurance-related delays are more common among younger adults.
Gastroenterologist Dr. Vincent DeRosa with Sutter Health said that kind of delay can happen when someone might assume symptoms such as rectal bleeding are caused by something less serious.
“Too many times I see patients, ‘Oh, I think it’s just hemorrhoids I’m bleeding from,’” DeRosa said. “Well, you can’t just assume that that’s the case.”
Beyond misdiagnosed symptoms, both specialists said many younger adults may also feel falsely reassured if they have no family history of colorectal cancers.
“Only about a third of colon cancers have family history involved,” DeRosa said. “So two-thirds of colon cancers are spontaneous mutations in those individual patients.”
Harnsberger said many patients are surprised by a colorectal cancer diagnosis because they often felt fine and assumed they weren’t at risk.
“The overwhelming majority will not have a genetic cause that is found, which can be very frustrating, and the overwhelming majority do not have a family history,” she said.
When is it Time for a Colonoscopy?
According to the 2026 study, stool testing was the preferred method of screening among young adults, citing its lower cost and greater convenience. However, the report also specified these tests are only intended for people at average-risk.
“If you have symptoms that raise a concern, especially any of these symptoms, you should not have a screening test,” Harnsberger said. “You should get what’s called a diagnostic colonoscopy.”
“You can’t really diagnose colorectal cancer in any other manner,” she said.
“The difference in a colonoscopy compared to any stool or blood test is that it is preventative because of its ability to remove polyps,” Harnsberger said.
Polyps are abnormal tissue that can be precursors to colorectal cancer, DeRosa said.
He said that colonoscopy remains the gold standard for colorectal cancer screening.
Locally, some uninsured Santa Barbara Neighborhood Clinics patients with a positive stool test may be eligible for free colonoscopies through a partnership involving the Cancer Foundation of Santa Barbara, Ridley-Tree Cancer Center and Sansum Clinic Gastroenterology, now part of Sutter Health.
Demystifying the Procedure
DeRosa said many people still expect colonoscopies to be worse than they are.
“I would say at least nine out of 10 patients that get a colonoscopy say, ‘Oh, that wasn’t so bad,’” he said.
DeRosa said one of the biggest changes in recent years has been the preparation process, which many patients still dread more than the procedure itself. He said some patients can now use pill-based prep instead of drinking a large volume of unpleasant liquid.
Patients may also be able to choose their level of sedation depending on insurance coverage, he said, adding that the procedure typically only takes 15-20 minutes.
DeRosa said another point people often do not realize is that if no polyps are found, patients generally do not need another colonoscopy for 10 years.
Cancer Treatment
The 2026 study found that five-year survival has improved over time, rising from about 50% in the mid-1970s to 65% in 2015 to 2021.
“And why has that improved? It’s because we’re diagnosing people at earlier stages due to more screening,” Harnsberger said.
Harnsberger said colorectal cancer is highly treatable when caught early, and that earlier diagnosis can reduce how extensive treatment needs to be. She said later-stage disease can require more invasive care and can have lasting effects on quality of life.
Those impacts can include permanent changes to bowel habits and other long-term challenges that may be especially disruptive for people still raising and earning for their young families, she said.
“Just because you don’t have a family history and you have no genetic cause doesn’t mean that it can’t happen to you,” Harnsberger said.