The overall incidence of colorectal cancer has been decreasing since the mid-1980s, but in the last decade there has been a concerning rise in early onset colon and rectal cancer, with more people under age 50 being diagnosed.
“It’s important to note that colorectal cancer is still most common in people over the age of 55,” said Blake Jones, MD, gastroenterologist with Endeavor Health. “Less than 15% of all cases are in patients under 50 and it’s an even smaller number for those under the age of 45, the age at which all adults are recommended to start screening.”
However, there is a birth cohort effect with Gen Xers and Millennials having significantly higher risk of developing early colorectal cancer than older Baby Boomers, added Dr. Jones.
“We’re also seeing the increase across all racial and ethnic demographics, where historically African Americans and Native Americans have been at higher risk.” Early onset colorectal cancer is more common in men than women, but it is growing in both.
There are several likely causes and the increase is probably related to complex, multifactorial reasons attributed mostly to environmental exposures, disease and lifestyle changes along with their potential impact on the intestinal microbiome.
“We don’t think that the increase is primarily related to genetics as our genes likely have not changed much that quickly, and most colon cancers are not clearly linked to genetics,” said Dr. Jones.
Among the factors that are likely at play are the rise in obesity and metabolic disease, both of which increase the risk for colorectal cancer. Alcohol consumption also increases risk, and the use of alcohol has risen until recently with Millennials and Gen Z now reporting less drinking.
The “Western diet” high in fats, processed meats, refined sugars and low in fiber, combined with an increasingly sedentary lifestyle in the last 50 years with more desk-bound jobs have also likely contributed to increasing cases of early onset colorectal cancer.
Environmental exposure to chemicals like polyfluoroalkyl substances (PFAS), even in-utero and peri-partum exposures, including rising rates of Cesarean sections and more antibiotics early in life, may be linked to increasing rates of early onset colorectal cancer.
“We know the microbiome is very important, we just don’t know exactly how it impacts the disease process and increased risk,” said Dr. Jones.
When patients ask what they can do to lower their risk “I always recommend a high fiber diet; fiber is the ultimate prebiotic. I tell people to eat a lot of fruits and vegetables, minimize consumption of red and processed meats, drink alcohol in extreme moderation and get at least the recommended 120-150 minutes of exercise a week to maintain a healthy weight,” added Dr. Jones.
Along with the rise in early onset colorectal cancer is an increase in more advanced stage cancers being diagnosed in younger people, said Dr. Jones. This may be because younger people are ignoring symptoms longer, assuming they are not at risk.
Rectal bleeding, sudden change in stool, weight loss, and iron deficiency anemia are all potential symptoms that should not be dismissed in an otherwise healthy young person, stressed Dr. Jones. Rectal cancer in particular can be symptomatic early on, he said. It’s important to let your doctor know about any changes in your health.
A colonoscopy is the gold standard for prevention and early detection of colorectal cancer. A colonoscopy can find and remove polyps before cancer develops. A screening colonoscopy should begin at age 45, or earlier depending on individual risk factors like family history. Ask your doctor when you should get screened.
