Colorectal cancer survivors face an increased risk of developing subsequent cancers, particularly second colorectal cancers and small intestinal cancers. That is the conclusion of a new study published early online in CANCER, a peer-reviewed journal of the American Cancer Society. The findings may help in the development of screening guidelines for patients with a history of colorectal cancer.

Studies have found that colorectal cancer survivors have a greater risk of developing another cancer compared with the general population. Amanda Phipps, PhD, MPH, of the University of Washington and Fred Hutchinson Cancer Research Center in Seattle, and her colleagues looked to see whether that increased risk differed for people depending on where their past cancer was located within the colon or rectum. "To our knowledge, this is the first study to look at risk of second cancer according to the specific anatomic subsite of a prior colorectal cancer," said Dr. Phipps. The research team also looked at whether there were certain kinds of cancer for which colorectal cancer survivors had a particularly increased risk.

The investigators analyzed information from 12 Surveillance, Epidemiology, and End Results cancer registries on people diagnosed with colorectal cancer between 1992 and 2009.

Individuals with a history of colorectal cancer had a 15 percent higher risk of developing a second cancer of any type than people in the general population. Those whose past cancers were located in the transverse to descending regions of the colon experienced the greatest increased risk for cancer overall (about a 30 percent increased risk) and for a second colorectal cancer (a two- to three-fold increased risk). Colorectal cancer survivors' risk of small intestinal cancer was particularly elevated - with a more than four-fold increased risk compared to the general population - regardless of where in the colon or rectum the cancer was located.

"In the long term, these findings may be useful in guiding strategies for cancer screening and surveillance after a first colorectal cancer diagnosis," said Dr. Phipps.