People born in 1990 experience twice the risk of developing colon cancer and 4 times the risk of developing rectal cancer compared with people born in 1950. Approximately 3 in 10 diagnoses of rectal cancer occur in patients younger than 55 years.1
Incidence rates for colorectal cancer are increasing in the so-called Generation X and in Millennials, with incidence of rectal cancer increasing particularly quickly.
In general, incidence of colorectal cancer has declined in the United States since the middle of the 1980s. Screening resulted in the steepest decline in the previous decade.
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These declines, however, are undermined by recent increases in incidence of colorectal cancer in patients younger than 50 years. Screening is not recommended in people in this age group who are at average risk.
To assess rates by 5-year age group and year of birth, researchers used age-period-cohort modeling, which is a quantitative tool that can separate what factors affect all age groups from what factors vary by generation.
This retrospective study examined data from 490,305 patients 20 years or older with invasive colorectal cancer diagnosed between 1974 and 2013 from the Surveillance, Epidemiology, and End Results program registries.
Colon cancer rates increased by 1% to 2% per year from the mid-1980s to 2013 in adults between 20 and 39 years. From the mid-1990s to 2013, colon cancer rates increased by 0.5% to 1% per year in adults aged 40 to 54 years.
Rectal cancer rates have increased for longer and faster, increasing approximately 3% per year between 1974 and 2013 in adults aged 20 to 29 years and at the same rate between 1980 and 2013 in adults aged 30 to 39 years. Rectal cancer rates increased 2% per year from the 1990s to 2013 in adults aged 40 to 54 years.
In contrast, rectal cancer incidence in adults aged 55 years and older have been decreasing for at least 40 years.
“Trends in young people are a bellwether for the future disease burden. Our finding that colorectal cancer risk for millennials has escalated back to the level of those born in the late 1800s is very sobering,” said Rebecca Siegel, MPH, of the American Cancer Society, Atlanta, Georgia, and a researcher in this study.
“Educational campaigns are needed to alert clinicians and the general public about this increase to help reduce delays in diagnosis, which are so prevalent in young people, but also to encourage healthier eating and more active lifestyles to try to reverse this trend.”
The researchers also suggest that the recommended age at which to initiate colorectal cancer screening in patients at average risk may need to be reconsidered.
Reference
1. Siegel RL, Fedewa SA, Anderson WF, et al. Colorectal cancer incidence patterns in the United States, 1974–2013. J Natl Cancer Inst. 2017 Feb 28. doi: 10.1093/jnci/djw322 [Epub ahead of print]
