MONDAY, March 5 (HealthDay News) -- New guidelines for colorectal cancer screening from the American College of Physicians (ACP) put the emphasis on individual risk.

People at average risk of developing colorectal cancer should get screened starting at age 50, whereas people at high risk -- those with inflammatory bowel disease or a personal or family history of the disease -- should get screened starting at age 40 or earlier, according to the updated recommendations. The guidelines appear in the March 6 issue of the Annals of Internal Medicine. March is U.S. National Colorectal Cancer Awareness Month.

In arriving at the new guidelines, the ACP evaluated the quality of colorectal cancer screening guidelines from many medical organizations to develop a "take-home message" both to help physicians make decisions and to help patients discuss screenings with their doctor, explained Dr. Amir Qaseem, director of clinical policy for the ACP and lead author of the guidelines.

"I think we are recommending something that the majority of organizations do: a risk assessment of people to see if they need to be screened earlier than 50 and for doctors to talk about the options," Qaseem said.

The guidelines recommend several screening options for average-risk patients: optical colonoscopy or flexible sigmoidoscopy, both of which involve inserting a narrow tube with a camera into the rectum, or stool sample tests.

All of these tests are thought to be similarly effective at preventing colorectal cancer-related death for average-risk patients, so the ACP decided that the choice of which to use should come down to factors such as patients' personal preferences and how well they are expected to tolerate the tests.

"Each has their benefits and harms," Qaseem said. The risk of bleeding and puncture of the colon may be higher in certain patients with invasive tests like optical colonoscopy and flexible sigmoidoscopy.

High-risk patients, on the other hand, should have an optical colonoscopy, which is the most sensitive test and the only one of the recommended tests that examines the entire colon.

Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Although screening can prevent deaths, only about 60 percent of adults aged 50 years and older in the United States get screened.

The fact that patients have many screening tests from which to choose will hopefully allow them to find one with which they are comfortable, Qaseem said.

"The ACP did a good service in developing a consensus guideline," said Dr. Frank Sinicrope, a professor of medicine and oncology at the Mayo Clinic in Rochester, Minn. "It's one source that internists and other physicians can go to."

Although other guidelines have included the importance of individual risk assessment, not all of them have embraced it, Sinicrope added. "We like to figure out who is average risk -- most of the patients -- and make a recommendation for them," he said. "[We] also consider higher risk [patients] who need a different recommendation."

People with a first-degree relative (parents, siblings, or children) who was diagnosed with colorectal cancer are at increased risk, and should start getting screened either at age 40 or 10 years before the age at which their relative was diagnosed, whichever comes first, according to the guidelines. Black people could also be at increased risk of developing colorectal cancer.

Getting a patient's family history is important for doctors to remember to do, Sinicrope said. "Family history data is elicited less frequently and is really not as detailed to do this properly," he said.

The guidelines also advise against screening people who are over 75 years old or who have a life expectancy of less than 10 more years because they are more likely to die of causes other than colorectal cancer, which takes a while to progress.

This is another instance where each patient should be assessed individually, however. "Some people at 75 may be healthier than some at 55, and you have to make a clinical judgment," Qaseem said. "In those patients it may be OK [to screen], because they may be living to 100."

The decision of which screening test to use also depends on what doctors feel comfortable with, Sinicrope said.

Although there is evidence to support using a newer form of noninvasive colonoscopy, called CT or virtual, colonoscopy, Sinicrope said there are not enough doctors who have expertise with the technology for it to be reliable. The ACP guidelines did not recommend CT colonoscopy.

In all, the ACP panel reviewed guidelines from five organizations that each focused on different aspects of screening: the U.S. Preventive Services Task Force, the Institute for Clinical Systems Improvement, the American College of Radiology, the American College of Gastroenterology, and the joint guidelines by the American Cancer Society, the U.S. Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.

More information

Find out more about colon cancer at the American Cancer Society.