New research from the American Cancer Society and recently published in Gut shows that colorectal cancer in young adults is on the rise in high-income countries. The study was conducted by Rebecca Siegel, MPH, and her colleagues.
Siegel’s team of researchers was interested in finding out more about early onset colorectal cancer on a global scale. To do so, they used cancer incidence registries to look at data for colorectal cancer occurrence in adults under 50 versus adults over 50. Their analysis combined data for 43 countries covering six continents.
Because of the general trend that we are seeing globally of declining or stable numbers of colorectal cancer diagnoses in adults over 50, the researchers were surprised to find the opposite happening in a significant number of countries for adults under 50. As they report in the study:
“In nine countries, specifically, the rise in early-onset CRC was in contrast to trends in those 50 and older, which were either dropping (Australia, New Zealand, Canada, Germany, and United States) or stable (Denmark, Slovenia, Sweden, and United Kingdom). In all but one of these countries with long-term data, the uptick in early-onset CRC began in the mid-1990s. In addition, in three countries (Cyprus, Netherlands, and Norway) where incidence rose in both younger and older age groups, the increase in young adults was twice as steep as that in older adults and also began in the mid-1990s.”
Why would more younger people be receiving more diagnoses of colorectal cancer across the board? The authors surmise that changes in early-life exposures are increasing the risk of colorectal cancer (CRC).
"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," said Ms. Siegel. "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."
The authors urge that more investigation into this topic is necessary in order to understand the long-term trends at play. Because colorectal cancer is the third most commonly diagnosed cancer worldwide, constructing a fuller image of CRC and early onset CRC is crucial in mitigating premature morbidity. Already CRC is on the decline in those over 50, assumedly because of improved screening; perhaps, the authors say, these screenings should extend to those under 50 as well.