Nearly 15 percent of patients diagnosed with colorectal cancer were younger than 50, the age at which screening recommendations begin.
The study by researchers at the University of Michigan Comprehensive Cancer Center also found that younger patients were more likely to have advanced disease. The authors suggest this is in part because they are diagnosed only after their cancers have grown large enough to cause symptoms.
"Colorectal cancer has traditionally been thought of as a disease of the elderly. This study is really a wake-up call to the medical community that a relatively large number of colorectal cancers are occurring in people under 50," says study author Samantha Hendren, M.D., M.P.H., associate professor of surgery at the University of Michigan Medical School.
"To put this in context, breast cancer screening often begins at age 40, and less than 5 percent of invasive breast cancers occur in women under that age. Our study found that about 15 percent of colorectal cancers are diagnosed before the screening age of 50," she adds.
The study identified 258,024 patients diagnosed with colon or rectal cancer from the Surveillance, Epidemiology and End Results database, a national database of cancer incidence. Results appear in the journal Cancer.
The authors found that younger patients were more likely to receive aggressive surgery and radiation therapy. In addition, this group had better survival rates, both overall and by stage. Among patients whose cancer had spread to distant organs, 21 percent of younger patients survived beyond five years, compared to 14 percent of older patients.
The improved survival could be in part due to the more aggressive treatment, the authors suggest.
The findings suggest the need for more awareness of warning signs of colorectal cancer: anemia, a dramatic change in the size or frequency of bowel movements, and bleeding with bowel movements. The authors also say that more people need to consider family history of colorectal cancer, which is a significant risk factor.
Should guidelines change to begin screening at an earlier age? Hendren says not so fast.
"This would be a big and costly change, and I don't know whether it would help more people than it would hurt," she says. "A lot of research would be required to understand this before any changes should be made."
Meanwhile, the more aggressive treatment and longer survival for younger patients suggest the need to improve long-term survivorship resources.
"The cancer community needs to prepare for the increasing number of very young colorectal cancer survivors who will need long-term support to cope with the physical and psychological consequences of their disease and treatments," Hendren says.
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