What is already known about this topic?

Colorectal cancer (CRC) incidence rates in young adults (under 50 years old) are increasing in many countries, despite decreasing rates in older adults. The extent to which this pattern occurs on a global scale remains unknown.

What are the new findings?

Colorectal cancer incidence rates are uniquely rising among young adults in nine high-income countries (Germany, USA, Australia, Canada, New Zealand, UK, Denmark, Slovenia, and Sweden) across North America, Europe, and Oceania, where rates in older adults are either stable or declining. Conversely, colorectal cancer rates have decreased among young adults in only three countries (Italy, Austria, and Lithuania), compared to 11 countries where rates in adults aged 50 and older are decreasing.

How might it impact clinical practice in the near future?

Raising awareness about the significant increases in colorectal cancer incidence could promote more diligent assessments of family cancer history by primary care clinicians, as well as closer monitoring of symptoms in younger patients, many of whom are diagnosed at later stages. These findings also highlight the need for earlier preventive screening for young adults concerning colorectal carcinogenesis.