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NEW YORK, Feb 28 (Reuters) - Colon and rectal cancer rates among younger adults are on the rise in the United States, suggesting the need for earlier screening, U.S. researchers said on Tuesday.
They found that people born in the 1990s are about twice as likely to be diagnosed with colon cancer as people born in the middle of the last century.
The trend was even worse for rectal cancers, showing that younger adults were about four times as likely to be diagnosed with those cancers versus older adults, the team found.
"The concern is if these increased risks are a bellwether for future risk," said Rebecca Siegel of the American Cancer Society, who led the study.
The research is the latest to show a steady increase in new diagnoses of colorectal cancer among adults under 50.
Better screening has helped lower colon and rectal cancer diagnoses among people 50 and older, but for those under 50, routine screening is not recommended.
In the latest study, researchers looked back at 40 years of data from 490,305 cancer cases. They found that the risk for colon or rectal cancers among people in their 20s fell between the late 1800s through the 1940s, when they reached their lowest level, and then began to increase, the team wrote in the Journal of the National Cancer Institute.
Among Americans in their 30s, rates of colon cancer diagnoses rose to 3.2 per 100,000 in 2013, from about 2.7 cases per 100,000 in 1988. Rates of rectal cancer diagnoses among these adults rose even more dramatically, jumping to 2.8 cases per 100,000 people in 2013, from 0.7 cases per 100,000 in 1980.
These increases were occurring even as rates of these same cancers were falling among older adults, due in large part to better cancer screening, the team said.
The study did not explore why cancer rates were rising among younger adults, but Siegel said it may be linked with changes in physical activity levels and diet.
The American Cancer Society is evaluating the evidence behind its colon and rectal cancer screening recommendations, and will consider whether a younger screening age is warranted, Siegel said.
Colon and rectal cancers are among the most common cancers in the United States. The American Cancer Society estimates that 95,520 cases of colon cancer and 39,910 cases of rectal cancer will be diagnosed in the country this year.
SOURCE: bit.ly/2lvlVPk Journal of the National Cancer Institute, online February 28, 2017. (Reporting by Andrew Seaman in New York; editing by Julie Steenhuysen and Jonathan Oatis)