Study Finds Sharp Rise in Colon and Rectal Cancers in Young Adults

Key Points

  • New cases of colorectal cancer are occurring at an increasing rate among young and middle-aged adults in the United States.
  • Among adults between the ages of 20 and 39, colon cancer rates increased by 1% to 2.4% annually since the mid-1980s; among adults between the ages of 40 and 54, they increased by 0.5% to 1.3% since the mid-1990s. Rectal cancer incidence rates among adults in their 20s have risen even more sharply, increasing by 3.2% per year from 1974 to 2013.
  • Because nearly one-third of patients with colorectal cancer are younger than age 55, the investigagtors propose that screening initiation before age 50 be considered.

Although the overall incidence rate of colorectal cancer in the United States has been declining rapidly since the mid-1980s, the decrease has been in older adults. During this same period, incidence rates have been increasing sharply for adults younger than age 50, finds a study by the American Cancer Society. Because colorectal cancer is increasing in people younger than age 55, the study authors propose that screening be considered before the age of 50. The study by Siegel et al was published in the Journal of the National Cancer Institute.

Study Methodology

The researchers analyzed colorectal cancer incidence trends by 5-year age groups and by year of birth from data provided by the Surveillance, Epidemiology, and End Results (SEER) program registries of 490,305 people aged 20 and older diagnosed with colon or rectal cancer from 1974 to 2013.

Study Findings

The researchers found that after decreasing in the previous decade, colon cancer incidence rates increased by 1.0% to 2.4% annually since the mid-1980s in adults aged 20 to 39 years and by 0.5% to 1.3% since the mid-1990s in adults aged 40 to 54; rectal cancer incidence rates have been increasing longer and more quickly (3.2% annually from 1974–2013 in adults aged 20–29). Among adults aged 55 years and older, incidence rates generally declined since the mid-1980s for colon cancer and since 1974 for rectal cancer.

From 1989–1990 to 2012–2013, rectal cancer incidence rates in adults aged 50 to 54 went from half those in adults aged 55 to 59 to equivalent (24.7 vs 24.5 per 100,000 persons: incidence rate ratios [IRR] = 1.01, 95% confidence interval [CI] = 0.92–1.10), and the proportion of rectal cancer diagnosed in adults younger than age 55 doubled from 14.6% (95% CI = 14.0%–15.2%) to 29.2% (95% CI = 28.5%–29.9%).

Age-specific relative risk by birth cohort declined from circa 1890 until 1950 but continuously increased through 1990. Consequently, compared with adults born circa 1950, those born circa 1990 have double the risk of colon cancer (IRR = 2.40, 95% CI = 1.11–5.19) and quadruple the risk of rectal cancer (IRR = 4.32, 95% CI = 2.19–8.51).

Initiating Early Colorectal Screening

Because nearly one-third of patients with colorectal cancer are younger than age 55, screening initiation before age 50 should be considered, concluded the study authors.

“Trends in young people are a bellwether for the future disease burden,” said Rebecca L. Siegel, MPH, Strategic Director of Surveillance Information Service at the American Cancer Society and lead author of the study, in a statement. “Our finding that colorectal cancer risk for millennials has escalated back to the level of those born in the late 1880s is very sobering. 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.”

Funding for this study was provided by the Intramural Research Department of the America Cancer Society and the Intramural Research program of the National Institutes of Health/National Cancer Institute.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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