People with average risk for colorectal cancer are not recommended to be screened until age 50, but the high number of patients with the disease have some researchers questioning whether guidelines should be changed. Photo by sheff/Shutterstock

ANN ARBOR, Mich., Jan. 25 (UPI) -- Screening for colorectal cancer is recommended starting at age 50, but 1 in 7 colorectal cancer patients are diagnosed before reaching screening age, according to a new study.

Researchers at the University of Michigan report younger patients have better survival rates, often due to more aggressive treatment because their cancer is more advanced -- and had only been caught because the cancer was large enough to cause symptoms.


Colorectal cancer is the second leading cause of cancer-related death and third most common cancer diagnosed in the United States, according to the Centers for Disease Control and Prevention.

Currently, guidelines suggest people with average risk for the cancers start being screened at age 50, while people with two or more diagnosed relatives should start screenings at age 40. Some doctors have been concerned about overscreening and its effects on patients, while others are not sure screening starts early enough.

"Colorectal cancer has traditionally been thought of as a disease of the elderly," said Dr. Samantha Hendren, an associate professor of surgery at the University of Michigan Medical School, in a press release. "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. 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."

For the study, published in the journal Cancer, researchers reviewed data on 258,024 patients with colorectal cancer collected for the Surveillance, Epidemiology, and End Results study between 1998 and 2011.

Among the patients with cancer, 37,847, or 15 percent, were younger than age 50. Younger patients were more likely to receive aggressive surgery on primary tumors and radiation therapy to reach cancer that has spread. For patients whose cancer spread, 21 percent of younger patients survived beyond five years, compared to just 14 percent of older patients.

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In addition to people paying more attention to family history, the researchers said higher awareness of colorectal cancer symptoms such as anemia, a dramatic change in the size or frequency of bowel movements, and bleeding with bowel movements would help.

The researchers suggest caution, however, in jumping to lower screening ages because of side effects and costs of unnecessary tests, among other reasons.

"This would be a big and costly change, and I don't know whether it would help more people than it would hurt," said Hendron. "A lot of research would be required to understand this before any changes should be made."