Colon cancer rates have been rising for decades among young people, study finds

Rates of colorectal cancer have been rising for decades among people too young for routine screening, a new study finds.

Systematic screening is recommended every 10 years from the age of 45; The new study focused on disease rates among children and adults ages 10 to 44, using data from the Centers for Disease Control and Prevention.

Colorectal cancer cases were increasing in all age groups, the researchers found.

“That means there is a trend,” said Dr. Islam Mohamed, an internal medicine resident at the University of Missouri-Kansas City who led the research. “We don’t know yet what to make of it, it could be due to lifestyle factors or genetics, but there is a trend.”

The findings, which have not yet been published in a peer-reviewed journal, will be presented later this month at the Digestive Disease Week conference in Washington, DC.

Despite these increases, the total number of cases among people under 40 remains low. In people under 30, cases remain extremely rare.

But with interest rates this low, any increase may take on greater significance.

The study found that colorectal cancer diagnoses among children aged 10 to 14 increased from 0.1 cases per 100,000 in 1999 to 0.6 per 100,000 in 2020, an increase of 500%. Cases among 15- to 19-year-olds jumped more than 300%, from 0.3 per 100,000 to 1.3 cases per 100,000 people. Among people aged 20 to 24, cases increased from 0.7 to 2 per 100,000 people, an increase of 185%.

“When you start with a very rare disease in a 15-year-old and add a few cases, you’re going to have a huge percentage increase,” said Dr. Folasade May, associate professor of medicine at the University of California. , Los Angeles Vatche and Tamar Manoukian Division of Digestive Diseases.

The increases were smaller for people over 25, but they also started with higher rates in 1999 than for younger groups. People over the age of 25 saw a more moderate, but still significant, increase in cases. The age group that was simply too young to be regularly screened – those aged 40 to 44 – saw a 45% increase, from about 15 cases per 100,000 people to about 21 cases per 100,000 people in 2020.

“We know that this disease is age-related, as you get older you are more likely to develop polyps and those polyps are more likely to turn into cancer,” May said.

May said that while the overall trend is alarming, it is reassuring to see that the oldest group saw the smallest percentage increase, since that group started with the highest number of cases. Data is still important, she said.

“Anyone between the ages of 15 and 19 being diagnosed with colorectal cancer is a bad thing,” May said.

“Changing the face of colorectal cancer”

Rates of colorectal cancer have increased in people under the age of 50 in recent decades. At the same time, cases and deaths from this cancer, once thought to affect only older people, are declining among people in their 60s and beyond.

“This reflects the changing face of colorectal cancer,” said Dr. Christopher Lieu, co-director of gastrointestinal medical oncology at the University of Colorado School of Medicine.

Rising rates among young people mean the higher risk of contracting the disease will likely stay with them for the rest of their lives, a phenomenon called the birth cohort effect, Lieu said. This means that a 40-year-old born in 1984 has a higher risk of colorectal cancer than a 40-year-old born in 1950.

“It’s not like at 50 the risk goes down, you carry that risk with you,” he said. “As young people age, I fear we will see an increase in colorectal cancer cases in screening groups. »

Doctors are still looking for answers to why cases of colorectal cancer are increasing among younger generations. But the reason doesn’t appear to be genetic, May said.

“There are a few cancers where we are now seeing earlier onset and they are probably linked. We don’t know why, but I think what we all agree on is that it’s an environmental problem rather than a genetic problem,” she said, noting that it could be linked to newer food processing methods or exposure to plastics.

Experts agreed that rising rates of colorectal cancer among younger generations were alarming, but did not support lowering the screening age for people at average risk. In 2018, the American Cancer Society dropped its recommendation for routine screening between ages 50 and 45.

“Before we talk about lowering the screening age by 45, we need to get these people tested. Less than 60% of people 45 and older have been screened,” May said.

Lieu said the data reinforces the importance of everyone in every age group being aware of the warning signs of colorectal cancer, and that doctors understand the importance of screening even their young patients for symptoms. appear.

“Younger patients are waiting longer to go to the doctor and are also having to wait longer to get their diagnosis because many of our patients are being told they are too young to have colorectal cancer,” Lieu said. “We don’t want our patients to go through this again, especially based on this data.”

The most common symptoms reported by study patients diagnosed with early-onset colorectal cancer were changes in bowel habits – constipation or diarrhea – abdominal pain, rectal bleeding and signs of anemia. Lieu said if someone, especially a young person, has blood in their stool, that’s a reason to make an appointment with a doctor.

One of the most powerful things a person can do for their health is to understand their family history, Mohamed said.

“Knowing their family history can provide them with valuable information about their own health,” he said, emphasizing that people with a family history of colorectal cancer should start getting screened 10 years before a sibling’s diagnosis or a sister or a parent.