Colorectal cancer increases among young people from high-income countries

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A new study of the American Cancer Society reveals that the incidence of colorectal cancer (CRC) is increasing exclusively in young adults in nine high-income countries that span three continents.

The study, which appears in the magazine Gut, finds that this increase is in contrast to the stable or decreasing trend in older adults possibly to changes in early exposures in life that are increasing the risk of CRC.

Colorectal cancer is the third most frequently diagnosed cancer worldwide, with some 1.8 million new cases in 2018. In general, the incidence of CRC is increasing in low and middle-income countries, but it begins to stabilize or decrease in high-income countries, especially those that have implemented detection.

However, studies of cancer registry data indicate that favorable overall trends in the United States and Canada are hiding an increase in young-onset RCC.

For more information on contemporary early-onset CCR patterns on a global scale, researchers led by Rebecca Siegel, an epidemiologist at the American Cancer Society, analyzed long-term population data on the occurrence of CRC in adults under 50 years of age compared to those over 50 in 43 countries covering six continents using high-quality cancer incidence data from population-based cancer registries.

Of the 36 countries with a sufficient number of cases to analyze trends, the incidence of CRC among adults under 50 years of age remained stable in the last ten years in 14 countries, decreased in three (Italy, Austria and Lithuania) and increased in 19 .

In nine of those 19, the increase in early onset CRC contrasted with trends in those over 50, who were falling (Australia, New Zealand, Canada, Germany and the United States) or stable (Denmark, Slovenia, Sweden and United Kingdom). In all but one of these countries with long-term data, the increase in early-onset CRC began in the mid-1990s.

In addition, in three countries (Cyprus, the Netherlands and Norway) where the incidence increased in the younger and older age groups, the increase in young adults was twice that in older adults and also began in the mid-decade. 1990. The incidence of early onset RCC increased more rapidly, 4.2 percent per year, in South Korea, where the rate is already higher among all the countries analyzed.

The decline in the incidence in older adults in many countries is partly attributed to the detection of CRC, which generally emerged in the last two decades and begins between the ages of 50 and 60.

However, Austria and Italy, two of the only three countries where the incidence of early-onset CRC is decreasing, have performed adult screening tests starting at age 40 and 45, respectively, since the early 1980s. In both Austria and Italy, decreases in CRC under 50 years were limited to the ages of 40-49 years.

“These patterns indicate possible changes in early-age exposures that lead to carcinogenesis of the large intestine and highlight the urgent need for research to explore the potentially unique etiology of young-onset RCC, Siegel notes. Although the absolute risk of CRC in adults under 50 is low in relation to older adults, disease trends in young age groups are a key indicator of recent changes in exposure to risk factors and often they presage the future burden of cancer. ”

The authors point out that, while other studies clarify the possible causes of the increase, doctors have the opportunity to help mitigate premature morbidity and mortality by CRC with active documentation of a family history of cancer; Timely follow-up of symptoms, regardless of the patient's age, and detection when appropriate.


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