Media release

From: The Lancet

The Lancet Oncology: Colorectal cancer rates continue to rise in young adults in many high-income countries, study suggests

Rates of colorectal cancer (CRC) increased in adults under the age of 50 in many high-income countries (HIC) up to 2017, suggests a paper published in The Lancer Oncology. An increase in rates was reported in 27 out of the 50 countries examined, with the greatest annual increases seen in New Zealand (4.0%), Chile (4.0%), Puerto Rico (3.8%), and England (3.6%). In contrast to the increasing rates in younger adults, CRC rates were found to remain stable or decrease in older adults in 20 of the countries examined.

CRC is the third most diagnosed cancer and the second leading cause of cancer death, responsible for more than 1.9 million new cases and almost 904,000 deaths in 2022 worldwide. The current study aimed to examine global rates of CRC in young (25-49 years)- versus older adults (50-74 years) using ten-year data up to 2017 from 50 countries. The study also found that increases in CRC rates in young adults were no longer limited to high income countries but were also seen in some low-income countries in Asia, Latin America and the Caribbean. However, the study only reports the rates of CRC up to 2017, so it may not accurately reflect current trends. Furthermore, the study used data from subnational registries that often represent a small fraction of a country’s population, which may limit the generalisation at the population level.

The authors highlight that the reasons for the increase in CRC rates in young adults remain largely unknown. They suggest that shifts in diet (from rich in low-fat and high-fibre foods, to increased consumption of red and/or processed meat, sugars, and convenience foods) and physically inactive lifestyles associated with economic wealth in young adults in HIC may be a factor explaining the generational shift in CRC rates, although further studies are needed to confirm this. While successful CRC screening programmes are thought to partially explain the decrease in rates for older adults in some countries, the escalating trend of CRC incidence among young adults could later lead to increased CRC incidence in older individuals, potentially impeding or reversing decades of progress made against the disease.

The authors say their findings underscore the need for intensified global efforts to understand the reasons for these trends, alongside an improved awareness of the unique symptoms of CRC, to help improve early detection and reduce rates of CRC in young adults.