Colon Cancer Screenings may be Missing up to 10 Percent of Colon Cancers

A recent study shows that up to 10 percent of colorectal cancers can be missed when current national screening guidelines are followed. As colorectal cancer is the third most common cancer in the United States and the second deadliest, this study led by researchers from the Huntsman Cancer Institute (HIC) at the University of Utah made findings based on nearly 127,000 individuals who underwent a colonoscopy in Utah between 1995 and 2009.

As there are genetic components to colon cancer, the study qualified an increased risk to first-degree relatives of patients with adenomas or advanced adenomas at 35 to 70 percent higher than in relatives of patients without these conditions. They study also detected smaller percentages of elevated risk in second and third-degree relatives.

"We expected to see increased risk in first-degree relatives, but we weren't sure the risk would also be higher for more distant relatives in multiple generations," said N. Jewel Samadder, MD, MSc, principal investigator of the study and an HCI investigator, via a press release. "The biggest surprise was the percentage of missed cancers under the current guidelines. We figured there would be a few percent, but 10 percent is a large number," he added.

For the general population, it's recommended that colon cancer screenings via conlonoscopy be conducted every 10 years starting at age 50. For those with first-degree relatives and the discovery of advanced adenomas, increased screenings are recommended with every five years at age 40.

"Our results support the current screening guidelines, but they also raise the issue of whether some level of more aggressive screening should be considered, not only for first-degree relatives of patients with polyps diagnosed at or below age 60, but also for those first-degree relatives of patients diagnosed above age 60.," said Samadder, via a release. "To validate other components of the current screening guidelines, we need to continue with a more in-depth examination of the risk of colorectal cancer in relatives of patients diagnosed with colorectal cancer or advanced adenomas, looking at factors such as the size of the polyp, the degree of cell abnormality and location of the tumor in the bowel."

The study looked at the colonoscopy results of Utah residents between 50 and 80 years of age, linking them with cancer and pedigree information from the Utah Population Database (PPDB).

"The records came from both Intermountain Healthcare and University of Utah Health Care, which represents 85 percent of all patient care in Utah and includes facilities from academic medical centers to small rural clinics," said Samadder, via the release. "No other study has combined genealogical and cancer data with records from two major health care organizations which have integrated electronic patient data."

More information regarding the study can be found via the journal Cancer.