African American and Hispanic adults under 50 also showed higher rates of colorectal cancer than non-Hispanic whites under 50. (Shutterstock/Africa Studio)
New US research has found that rates of colorectal cancer in American adults under the age of 50 are increasing.
Carried out by researchers at The University of Texas at Austin, the new study looked at information gathered from the National Cancer Database registry, which includes more than 70 percent of new cancer cases in the United States, to look at trends in colorectal cancer cases since 1970.
The findings, published in CANCER, a peer-reviewed journal of the American Cancer Society, showed that the number of American adults diagnosed with colorectal cancer under age 50 has continued to increase over the past decade, rising from 10 percent in 2004 to 12.2 percent in 2015.
Moreover, 51.6 percent of those under 50 were diagnosed with more advanced stages of colorectal cancer (stage III/IV) compared to 40 percent of those over the age of 50.
African American and Hispanic adults under 50 also showed higher rates of colorectal cancer than non-Hispanic whites under 50.
Rates of colorectal cancer diagnosis in young adults have also increased across income levels, although the highest rate of diagnoses were found in the top income category.
"Several studies have shown that the rates of colorectal cancer in younger adults have risen slowly in the US since the 1970s, but for practicing physicians, it feels like we are seeing more and more young people with colorectal cancer now than we were even 10 years ago," said lead author Dr. Boone Goodgame. "Until just last year, guidelines recommended colon cancer screening beginning at 50. Now many guidelines do recommend screening at age 45, but most physicians and patients don't appear to be following those recommendations."
Dr. Goodgame noted that the cause of the increasing rates of colorectal cancer in those under 50 is still unclear, although he points out that new research suggests that it could be due to a combination of increases in body weight and changes in gastrointestinal bacteria.
Previous research has also linked colorectal cancer to too much sedentary time, in particular watching TV, too much alcohol, too much processed meat, and a lack of exercise.
A balanced healthy diet, in particular one which includes nuts and plenty of whole grains, increasing physical activity, and drinking little alcohol has been linked to a lower risk.
Guidelines from the American Cancer Society suggest that average-risk adults age 45 years and older undergo regular screening colorectal cancer screening.