In oncology, 30 is the new 60
Key Takeaways
Industry Buzz
"Ongoing behaviors such as dietary patterns may continue to drive malignancy risk, so lifestyle changes that are made in early adulthood could still reduce risk of CRC... For instance, if colibactin-expressing E. coli are primarily able to induce genotoxicity in the setting of a Western diet, changing diet may reduce further genotoxicity in those who are colonized with colibactin-expressing E. coli.” — Jonathan Jacobs, MD, gastroenterologist at UCLA
"We need to have a very low threshold to investigate the possibility of a colon cancer diagnosis in younger adults when they present with possibly related symptoms, whereas in the past we might have discounted this possibility due to their age alone.” — Christopher Chen, MD, specialist in oncology, hematology and gastrointestinal cancers at Stanford
Rates of colon cancer in young people have doubled over the past two decades.[]
But what can physicians do to address the challenge?
“The rise in incidence of early-onset colorectal cancer (EOCRC) is a major concern for the medical community. At the current trajectory, we anticipate that CRC is expected to become the most common cancer among young adults by 2030. This has already led to a change in screening guidelines recently to now recommend CRC screening starting at age 45 instead of 50,” Jonathan Jacobs, MD, a gastroenterologist at UCLA, tells MDLinx.
“Since population genetics would not have changed over such a short time,” he observed, “this likely reflects a combination of environmental exposures and behavioral changes in recent years such as widespread adoption of low-fiber Western diets. These factors may act by changing the gut bacteria, which have been demonstrated in extensive studies to influence CRC development and progression.”
Colibactin and colon cancer
In April 2025, Nature published results of an international study that indicated a link between colibactin, a type of toxin that can be created by E. coli and other forms of bacteria, and colon cancer in younger people across the globe.[]
Experts say the finding represents an important step forward in understanding why more young people are getting colon cancer.
“This association between colibactin and colon cancer is a provocative finding, and suggests that a patient’s gut microbiome early in life may play an important role in the rise of colon cancer later in life. This warrants additional investigation to further explore and validate this hypothesis,” Christopher Chen, MD, a specialist in oncology, hematology and gastrointestinal cancers at Stanford, tells MDLinx.
Turning back the clock...
Factors that have been linked to colorectal cancer in young people include long-term or recurrent antibiotic use in early life and poor dietary patterns.[][]
Experts say these patterns present an important challenge for physicians in helping both current and future generations of patients.
“We can’t go backwards, but we can only learn from the past and prevent the next generation from [getting] into this situation,” Ronald Hsu, MD, a gastroenterologist at UC Davis, tells MDLinx.
Dr. Jacobs agrees: “While we can't turn back time, we can still act on knowledge of the factors that drive EOCRC risk in at least two ways. First, if we characterize microbes and their products such as colibactin that are driving risk for EOCRC, we could potentially in the future identify young adults who are at the greatest risk for EOCRC and may warrant screening at an earlier age than of 45 years."
"Screening colonoscopy allows for removal of polyps before they have the opportunity to develop into EOCRC, thereby preventing cancer even if we can't change the past exposures and behaviors that led to early colorectal neoplasia,” Dr. Jacobs says.
“Second, ongoing behaviors such as dietary patterns may continue to drive malignancy risk, so lifestyle changes that are made in early adulthood could still reduce risk of CRC over time," he continues. "For instance, if colibactin-expressing E. coli are primarily able to induce genotoxicity in the setting of a Western diet, changing diet may reduce further genotoxicity in those who are colonized with colibactin-expressing E. coli.”
A low threshold for investigation
With just 5 years until colorectal cancer is expected to be the most common form of cancer among young people,[] Dr. Chen says physicians need to be vigilant in properly assessing young adult patients.
“We need to have a very low threshold to investigate the possibility of a colon cancer diagnosis in younger adults when they present with possibly related symptoms, whereas in the past we might have discounted this possibility due to their age alone. Secondly, we need to continue to rigorously investigate the causes of early-onset colon cancer so that we can hopefully mitigate this growing problem for generations to come.”