Early-onset colorectal cancer, diagnosed in individuals under 50, is rising at an alarming rate across the globe. A study led by the American Cancer Society (ACS) has found that incidence rates for this type of cancer have increased in 27 of 50 countries examined, while rates in older adults remain stable or decline in many of those same regions. The findings, published in The Lancet Oncology, highlight a growing global health concern that calls for immediate attention.
“The increase in early-onset colorectal cancer is a global phenomenon,” said Hyuna Sung, PhD, senior principal scientist at the American Cancer Society and lead author of the study. “Previous studies have shown this rise in predominately high-income Western countries, but now, it is documented in various economies and regions worldwide.”
The study analyzed colorectal cancer incidence trends from 50 countries using data from the Cancer Incidence in Five Continents Plus database. Researchers focused on two age groups: younger adults aged 25–49 and older adults aged 50–74. They found that while rates in older adults stabilized or declined in many regions, early-onset cases surged, particularly in countries such as New Zealand, Chile, and Puerto Rico, where annual increases exceeded 3.8%.
Interestingly, the trends varied by sex and region. In some countries, including England, Norway, and Australia, rates increased faster among women, while in others, such as Chile and Argentina, men experienced higher rates of early-onset colorectal cancer. Despite these regional and demographic differences, the overall trajectory points to a troubling global rise in young adult cases.
The researchers emphasized that the causes of this trend are not yet fully understood but are likely tied to changes in lifestyle factors such as diet, physical inactivity, and excess body weight. These factors are particularly concerning in high-income countries, where they may contribute to increased risk in younger populations.
“This flagship study reveals that increasing rates of early-onset bowel cancer, affecting adults aged 25–49, is a global issue,” said Michelle Mitchell, chief executive of Cancer Research UK. “While it’s important to note that rates in younger adults are still very low compared to people over 50, we need to understand what’s causing this trend in younger people.”
The findings underscore the importance of raising awareness about colorectal cancer symptoms among younger people and their healthcare providers. Symptoms such as rectal bleeding, abdominal pain, altered bowel habits, and unexplained weight loss often go unrecognized in younger populations, leading to delays in diagnosis and treatment.
Sung highlighted the urgent need for innovative prevention tools and strategies. “The global scope of this concerning trend highlights the need for innovative tools to prevent and control cancers linked to dietary habits, physical inactivity, and excess body weight,” she said. Efforts are already underway, including a £20 million Cancer Grand Challenges grant awarded to a global team investigating the causes of bowel cancer in younger adults and strategies to prevent it.
