US colorectal cancer rates rose in 2023 for the first time in over 20 years

For two decades, colorectal cancer in the US had been on a long slide. Using registry data covering 45.8% of the population, a new NEJM Evidence report finds the age-adjusted rate fell from 55.2 cases per 100,000 people in 2000 to 36.7 in 2022. In 2023 it rose to 38.3, which the authors describe as the first apparent increase since that registry series began.

The sharpest rise was at ages 45 to 49, at 12.76% a year from 2019 to 2023. Part of that has a known explanation: screening now starts at 45 instead of 50, so more existing cancers are found sooner.

That explanation doesn't cover older people. Rates also rose at ages 65 to 69 and stopped falling at 70 to 74. Leaving out the 2020 and 2021 pandemic years didn't make the increase disappear.

Registry numbers show a trend, not its cause, and the researchers haven't identified which risk factors are behind it. One year's uptick also has to hold up in future updates before it counts as a new direction.