Colon cancer screening guidelines may miss 10 percent of colon cancers
For people with a family history of adenomas (colon polyps that lead to colon cancer), up to 10 percent of colorectal cancers could be missed when current national screening guidelines are followed. Colorectal cancer is the third most common cancer in the United States and the second deadliest.
In the largest population-based study to date, researchers from Huntsman Cancer Institute (HCI) at the University of Utah made this finding based on nearly 127,000 individuals who underwent colonoscopy in Utah between 1995 and 2009. The results appear online in “Early View” of the journal Cancer.
Family history of colon cancer is widely accepted as a factor that increases risk for the disease. This study quantified the increased risk to first-degree relatives (parents, siblings, children) of patients with adenomas or advanced adenomas at 35 to 70 percent higher than in relatives of patients without these conditions. The study also detected smaller percentages of elevated risk in more distant second- (aunts and uncles, grandparents) and third-degree relatives (cousins, nieces and nephews, great-grandparents).
“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. “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, current national colon cancer screening guidelines recommend colonoscopy every 10 years starting at age 50. For first-degree relatives of people diagnosed with colorectal cancer or advanced adenomas before they were 60 years old, increased screening is recommended—colonoscopies every five years starting at age 40. The screening recommendations for more distant relatives of people diagnosed before 60 and for all relatives of people diagnosed at or after age 60 are the same as for the general public.
“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. “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 examined colonoscopy results from Utah residents between 50 and 80 years of age, linking them with cancer and pedigree information from the Utah Population Database (UPDB). “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. “No other study has combined genealogical and cancer data with records from two major health care organizations which have integrated electronic patient data.”
What Is Colorectal Cancer Screening?
A screening test is used to look for a disease when a person doesn’t have symptoms. (When a person has symptoms, diagnostic tests are used to find out the cause of the symptoms.)
Cancer screening tests, including those for colorectal cancer, work best when they can help prevent cancer or find it early, when treatment works best.
Screening Saves Lives
Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find precancerous polyps, so that they can be removed before they turn into cancer. Screening tests can also find colorectal cancer early, when treatment works best.
Regular screening, beginning at age 50, is the key to preventing colorectal cancer. The U.S. Preventive Services Task Force (USPSTF) recommends screening for colorectal cancerExternal Web Site Icon using high-sensitivity fecal occult blood testing, sigmoidoscopy, or colonoscopy beginning at age 50 years and continuing until age 75 years.
Co-authors of the study include Thérèse Tuohy, PhD; Geraldine Mineau, PhD; Richard Pimentel, MS; and Randall Burt, MD, all from HCI; and Kerry G. Rowe, MS, from Intermountain Healthcare. The research was supported by NCI grants P01-CA073992 (RWB) and R01-CA040641 (RWB). Partial support for the Utah Population Database is provided by Huntsman Cancer Institute, Huntsman Cancer Foundation, and the HCI Cancer Center Support grant, P30CA042014 from the National Cancer Institute. The Utah Cancer Registry is funded by contract HHSN 261201000026C from the National Cancer Institute’s SEER program, with additional support from the Utah State Department of Health and the University of Utah.
The mission of Huntsman Cancer Institute (HCI) at The University of Utah is to understand cancer from its beginnings, to use that knowledge in the creation and improvement of cancer treatments, to relieve the suffering of cancer patients, and to provide education about cancer risk, prevention, and care. HCI is a National Cancer Institute-designated cancer center, which means that it meets the highest national standards for world-class, state-of-the-art programs in multidisciplinary cancer research and receives support for its scientific endeavors. HCI is also a member of the National Comprehensive Cancer Network (NCCN), a not-for-profit alliance of the world’s leading cancer centers dedicated to improving the quality and effectiveness of care provided to patients with cancer.
Cancer of the colon and rectum invades and damages adjacent tissues and organs. Cancer cells also can break away and spread to other parts of the body (such as the liver and lung) where new tumors grow. The sprocess whereby colon cancer preads to distant organs is called metastasis, and the new tumors are called metastases. Once metastasis has occurred in colorectal cancer, a complete cure of the cancer is unlikely.
Colorectal cancer is both preventable and curable. Colorectal cancer is prevented by removing precancerous colon polyps . It is cured if it is found early and is surgically removed before it spreads to other parts of the body. The National Polyp Study showed in its surveillance program that individuals who had their polyps removed experienced a 90% reduction in the incidence of colorectal cancer. The few patients in the study who did develop colorectal cancer had their cancer discovered at early, surgically or endoscopically curable stages. Since most colon polyps and early cancers are silent (produce no symptoms), it is important to do screening and surveillance for colon cancer in patients without symptoms or signs of the polyps or cancers. Recommendations for cost-effective public screening and surveillance have been promulgated and endorsed by numerous societies including the American Cancer Society, the National Cancer Institute, American College of Gastroenterology, American Medical Association, American College of Physicians, etc.
University of Utah Health Sciences