September 05, 2019
2 min read

‘We should be unsettled’: Colorectal cancer incidence rising among young adults

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Darrell Gray II

Researchers from the American Cancer Society have found increasing incidence of colorectal cancer among young adults in nine high-income countries where population-based screening initiatives have led to stabilized or decreasing trends among older adults, according to study results published in Gut.

“These patterns potentially signal changes in early-age exposures conducive to large bowel carcinogenesis and highlight an urgent need for research to explore the potentially unique etiology of young-onset CRC,” Rebecca Siegel, MPH, of the intramural research department at the American Cancer Society and lead author said in a press release. “Although the absolute risk of CRC in adults younger than 50 years is low relative to older adults, disease trends in young age groups are a key indicator of recent changes in risk factor exposures and often foreshadow the future cancer burden.”

Researchers analyzed long-term data from the Cancer Incidence in Five Continents database to determine CRC occurrence in adults older and younger than 50 years from 43 countries.

In 36 countries that had enough data for trend analysis, Siegel and colleagues found that CRC incidence was stable in 14 and decreased in three. However, in nine countries where CRC trends among individuals aged 50 years and older have decreased or remained stable, investigators found that rates of early-onset CRC were rising (Australia, Canada, Denmark, Germany, New Zealand, Slovenia, Sweden, the United Kingdom and the United States). In these countries, researchers started to see incidence of CRC in younger adults increase in the mid-1990s.

Among these countries, New Zealand had the highest 10-year annual average percent change in CRC incidence among adults aged 20 to 49 years (4%; 95% CI, 2.1%–6%), followed by the U.K. (3.3%) and Canada (2.8%).

Austria and Italy, two of the countries in which early-onset CRC declined, have been screening individuals at ages 40 and 45 years, respectively, since the early 1980s. Screening in the countries that experienced decreasing or stabilized rates among older individuals generally occurs between ages 50 and 60 years.

Darrell Gray II, MD, MPH, associate professor of medicine at The Ohio State University College of Medicine, told Healio Gastroenterology and Liver Disease that all the stakeholders, from clinicians to researchers to advocates, need to take the findings of the study seriously and put in a combined effort to find out what is causing this uptick, which is not yet fully understood.

“We should feel unsettled by these findings,” Gray said. “But also invigorated to both tackle the hard questions of why this is happening and to dedicate time and resources to research, as well as community outreach and engagement efforts to address this issue.”

Gray also believes the effort will require greater awareness throughout communities and a better understanding of individual risk for CRC.

“One step could be as simple as having more discussions within our families, talking more about family history and better understanding risk factors for colorectal cancer,” he said. “Also, there needs to be a greater awareness of alarm symptoms for which people should seek medical evaluation. Patients and doctors should not ignore symptoms such as rectal bleeding or signs such as anemia, regardless of the age of the patient. While these are not commonly due to colorectal cancer, timely evaluation of them is extremely important.” by Alex Young

Disclosures: The study’s authors report no relevant financial disclosures. Gray reports consulting for Genentech, particularly for their “Love Your Colon” campaign.