The number of deaths from colorectal cancer among young people is expected to double in two decades by 2030, experts warn.
The cancer — which is particularly difficult to treat due to its late diagnosis and wide-ranging symptoms — is also expected to become the leading cause of cancer death in people under the age of 50 by the end of the decade.
Doctors are still trying to figure out what’s behind the unprecedented rise, but theories include modern diets, antibiotic use, and even mold.
Dr. Christopher Lieu, co-director of gastrointestinal medical oncology at the University of Colorado Medicine, said: “Colon cancer will be the leading cause of cancer-related death in [patients] 20 to 49.”
Speaking at a cancer conference in Chicago on Saturday, he added, “This is a huge issue.”
Data from JAMA Surgery, to which Dr. Lieu referred to in his presentation this weekend, showed that colon cancer is expected to increase by 90 percent in people aged 20 to 34.
The same data shows that rectal cancer in the youngest age group will rise by 124 percent
Cancers of the colon and rectum are currently the third most common type in the US and the third leading cause of death for both men and women.
Dr. Lieu said both diagnosis and death rates are rising in young people, even as rates are declining in older populations.
The American Cancer Society estimates that about 153,000 cases of colon cancer will be discovered this year, including 19,500 among people under the age of 50.
About 52,550 people are expected to die from the disease.
In a March report from the ACSscientists warned that the rate of colon cancer in people aged 50 to 54 nationwide was now nearly 60 per 100,000.
In comparison, between 1975 and 1979, the rate was around 40 per 100,000, indicating a 50 percent increase in about 45 years.
About 43 percent of the diagnoses were in people 45 to 49 years old.
The US is not the only country with these alarming figures. A 2023 assessment found that while the US had an early-onset colorectal cancer rate of 12.4 per 100,000 people, Australia had 13.5, Norway had 10.5, Korea had 10.1, and the United Kingdom had 9.3.
“We don’t know why this trend is seen in many countries with different diets and exposures and environmental factors,” Dr Lieu said.
A 2020 study from Colorectal Cancer Alliance found that many patients with colorectal cancer symptoms were initially misdiagnosed or discharged
Dr. Lieu said that based on data from JAMA surgerybetween 2010 and 2030, colon cancer will have increased by 90 percent in people aged 20 to 34. In the same age group, rectal cancer will have increased by 124 percent.
Experts have often blamed unhealthy diets, alcohol consumption and sedentary lifestyles for this shift, although some studies suggest otherwise.
A 2021 studyfor example, found that early-onset cancer patients were less likely to be obese or smokers than their older counterparts.
Dr. Lieu pointed to the health effects and exposures that early-onset colorectal cancer patients have already had at birth.
Dr. Christopher Lieu of the University of Colorado Medicine said the rise of colon cancer in young people is “a huge problem.”
a study published in April examined how being born via c-section influenced the likelihood of developing early-onset colon cancer. The researchers found that women who were born via cesarean section were more likely to develop colorectal cancer earlier in life than women who were born vaginally. There was no connection between men.
In addition, the use of antibiotics has been shown to influence this risk. A study in the journal Gut found that long-term antibiotic use resulted in an increased risk of early-onset colon cancer. However, it was also associated with a lower risk of rectal cancer.
And research presented at the annual meeting of the American Society of Clinical Oncology this weekend showed that the fungus Cladosporium sp. was more common in tumors of young patients than in older subjects.
It is still unclear how Cladosporium sp. could lead to this increase in cases, but the researchers think it could damage cell DNA. This can turn them into cancer cells.
These environmental factors have a lasting impact on the gut microbiome, which experts believe could increase the risk of colorectal cancer, even when exposure was limited to early life.
“People carry this increased risk with them as they age,” Dr Lieu said.
Part of what makes it difficult to diagnose colorectal cancer is the symptoms, which can often be attributed to other conditions. However, some stand out more than others.
A study published last month in the Journal of the National Cancer Institute found that the most commonly reported symptoms were abdominal pain, blood in the stool, diarrhea, and iron deficiency anemia.
In addition, a 2020 study of Colorectal Cancer Alliance, 68 percent of participants said they experienced blood in their stool. The mean age of the participants was 42 years.
“This is a concerning finding and something that should never be taken lightly, especially by primary care providers,” said Dr Lieu.
The same study also found that many patients with colorectal cancer symptoms were initially misdiagnosed or discharged.
More than half of respondents said they had been misdiagnosed with conditions such as hemorrhoids, irritable bowel syndrome, anemia and mental health problems. And patients ages 19 to 39 were more likely to feel rejected by their provider.
In one study, with just one symptom, it took an average of 10 months to be diagnosed with colorectal cancer. Those with at least three symptoms were diagnosed after an average of five months.
“Five months is still far too long to be diagnosed with clearly a very deadly disease,” Dr Lieu said.
Spending extended periods of time without a diagnosis can cause colorectal cancer to progress to later stages, making it more difficult to treat.
“Some of our stage IV patients waited more than a year for diagnosis from the onset of their symptoms,” Dr Lieu said. “We shouldn’t be surprised if they show up in later stages of the disease.”
Amid concerns about the rising rate among younger adults, the US Preventive Services Taskforce lowered the screening age from 50 to 45 in 2021.
This is usually a colonoscopy, which involves inserting a camera into someone’s rectum, looking for growths or changes in their intestines.
However, patients under the age of 45 are less likely to be screened because they do not fall within the recommended age range.
A 2017 study in the journal Clinical Gastroenterology and Hepatology found that people under 50 tended to wait two months longer to seek medical attention after first noticing symptoms than people over 50.
In a 2019 study63 percent of colorectal cancer patients did not even know that this type of cancer can occur in people under the age of 50.
Dr. Lieu said in a call to action that educating doctors and patients about the signs to watch for and expanding risk assessments and genetic testing could help researchers better understand what’s driving this increase.
“Awareness is key,” he said.