Colorectal cancer is now the leading cause of cancer death in adults younger than 50, according to a report published Thursday in the Journal of the American Medical Association (JAMA). Since 1990, overall cancer deaths among this age group have decreased, but colorectal cancer (of the colon or rectum) has been an outlier, with mortality increasing every year.
“It’s really startling and really disappointing and scary,” Melissa Lumish, MD, an assistant professor at the Case Comprehensive Cancer Center, told Health. “At the same time, it’s not totally shocking to me because we know that this has been a disease on the rise in people under age 50.”
For the new study, researchers tracked fatalities of people younger than 50 from the five leading causes of cancer death over the past three decades. In 1990, lung and bronchus cancer caused the most cancer deaths in this age group, followed by breast cancer, leukemia, brain and other nervous system cancers, and colorectal cancer.
Over time, cancer death rates began to decline. Each year since 2014, deaths from lung cancer have dropped by 5.7%, breast cancer by 1.4%, leukemia by 2.3%, and brain cancer by 0.3%. Meanwhile, colorectal cancer deaths rose by 1.1% annually. Eventually, it became the leading cause of cancer death.
Lilian Chen, MD, chief of Colon & Rectal Surgery at Tufts Medical Center, told Health the new report is “deeply concerning” and should serve as “a wake-up call.” “Every other leading cancer death rate is declining,” Chen said. “That tells us something fundamentally different is happening with colorectal cancer in younger adults.”
The new study’s findings align with a rise in colorectal cancer incidence rates among people under 50. Research has shown that since 2000, colorectal cancer cases in this age group have increased by almost 1.4% annually, while rates among adults over 50 have declined by almost 3.1% each year.
Scientists have yet to pinpoint the exact reasons behind this trend, but Chen said it is likely due to multiple factors. “Changes in diet, rising obesity rates, sedentary lifestyles, alterations in the gut microbiome, and environmental exposures may all be contributing,” she said.
Lumish emphasized that it’s still too early to say what’s behind the rise. “Many of us see the young, fit person who exercises five times a week and drinks no soda and eats a mostly vegetarian diet—and they still are coming in with these cancers,” she said.
Younger adults also tend to get diagnosed only after the disease has progressed. About three in four colorectal cancer patients younger than 50 are diagnosed with an advanced case, “which helps explain why mortality is increasing despite advances in treatment,” Chen said.
“What makes this especially striking is that it mirrors what I am seeing in my own clinical practice,” she added. “I am treating more and more younger patients with colorectal cancer, and many of them are being diagnosed at later stages.”
Staying up to date on your colorectal cancer screenings is crucial, experts said. Current guidelines recommend starting screening at age 45, or earlier for people with a family history or other risk factors.
Lumish noted that people with a first-degree relative who was diagnosed before 50 should begin screening 10 years earlier than the age at which the family member was diagnosed. “So if you have a sister or brother or parent who was diagnosed with colorectal cancer at 45, that person should be screened at 35,” she explained.
Half of those diagnosed with colorectal cancer before age 50 are actually younger than 45, so it’s also important to be aware of the warning signs. A 2023 study identified four red flags that are more common in adults under 50:
“If you are experiencing concerning or persistent symptoms, people should speak to their doctor and learn about their choices for colon cancer screening,” Chen said. “Early detection is the single most powerful tool we have to reverse this trend.”
