By Denise Mann
Now, new research suggests that certain lifestyle factors, such as eating lots of red meat and heavy alcohol consumption, may play a role in this increase.
"The occurrence of colorectal cancer in people less than 50 years of age is increasing in many countries, but the causes of this are poorly understood [and] our research is the first large-scale effort to identify these causes, providing early clues for identification of those most at risk," said study author Richard Hayes, a professor of population health and environmental Medicine at NYU Langone Health in New York City.
The findings dovetail with the announcement on Tuesday from the U.S. Preventive Services Task Force that it will lower the recommended age for first screening colonoscopy from 50 to 45 in people at average risk for colon cancer.
To get a better handle on what lifestyle factors may be playing a role in the uptick of colon cancer in young people, researchers analyzed data from 13 studies that included people who developed colon cancer before 50 and after 50, along with their counterparts without a history of colon cancer.
In addition to eating more red meat and consuming excess amounts of alcohol, people who were diagnosed with early-onset colon cancer didn't take nonsteroidal anti-inflammatory drugs (NSAIDS) such as aspirin regularly and did not get as far in school as their counterparts who did not develop cancer before age 50. Daily low-dose aspirin may lower colon cancer risk.
All of these factors also raise risk for developing colon cancer after age 50. By contrast, body mass index (BMI, an estimate of body fat based on height and weight) and smoking were not risk factors in early-onset colon cancer, but they were in later-onset cases.
When researchers broke down colon cancer risks by where the cancer was found, they noted that people who didn't eat enough fiber-rich foods were more likely to develop cancer in their rectum than their colon.
These risks were similar among men and women, said Hayes. The research did not include enough Black or nonwhite people to draw any conclusions about the role of race in risk of colon cancer before age 50, he said.
"It is important that this area of research expand to other racial and ethnic groups in the future," Hayes said.
The study was published in the June 2021 issue of the journal JNCI Cancer Spectrum.
"This study tells us a little bit about younger folks who have these risk factors and if they came in with abdominal symptoms and had some of these risks, we may recommend earlier or more frequent screening," said Dr. Neeha Zaidi, an assistant professor of oncology at Johns Hopkins Medicine in Baltimore. She was not involved in the new study.
The increase in colon cancer among people younger than 50 is likely not driven by genes, said Heather Hampel, a genetic counselor at the Ohio State University Comprehensive Cancer Center–James Molecular Carcinogenesis and Chemoprevention Program.
"It's good that the new paper confirmed some of these risks that we have seen in other studies, but we were hoping to identify something specific to early-onset colorectal cancer that might be new since 1960," she said.
"There is no smoking gun for why early-onset colon cancer is increasing so dramatically," said Hampel, who wasn't part of the study.
Until researchers locate the cause, the best way to stay ahead of colon cancer is to follow screening guidelines, know your family history, and eat a healthy diet, she said.
Learn more about the new screening recommendations for colon cancer at the U.S. Preventive Services Task Force.
SOURCES: Richard Hayes, DDS, PhD, MPH, professor, population health, environmental medicine, NYU Langone Health, New York City; Neeha Zaidi, MD, assistant professor, oncology, Johns Hopkins Medicine, Baltimore; Heather Hampel, LGC, MS, genetic counselor, Ohio State University Comprehensive Cancer Center–James Molecular Carcinogenesis and Chemoprevention Program, Columbus; JNCI Cancer Spectrum, June 2021