You may be among a newly discovered group that’s at increased risk for colorectal cancer, the second-most deadly malignancy in the US. But odds are that you don’t know it—and neither does your doctor—so you’re probably not getting the testing you need…even if you’re following the current colorectal cancer screening guidelines to a T.
This recently discovered risk has to do with family history—not your relatives’ history of actual colorectal cancer, but rather their history of polyps (also calledadenomas), which are benign growths in the colon or rectum that may someday become cancerous. The increased risk isn’t limited just to close relatives, either. In fact, the way the current guidelines are written, for 10% of people with a family history of these polyps, screening comes too late. Here’s what you and your clan need to know…
FAMILY TIES EXPLORED
Colonoscopy is one of the few cancer screenings that’s proven to save lives. Not only can it detect colorectal cancer at its early and most treatable stages, it also allows doctors to find and remove precancerous growths before they have a chance to turn into cancer.
More on Colon Polyps
Current guidelines: For the general population, screening colonoscopy is recommended every 10 years starting at age 50. Increased screening is advised for the parents, children and siblings of any patient diagnosed prior to age 60 with either colorectal cancer or an advanced adenoma (an adenoma with precancerous pathological features and/or a diameter of one centimeter or more). For these close family members, colonoscopy is recommended every five years starting at age 40 or starting 10 years earlier than the age at which their relative was diagnosed. (For instance, if your father was diagnosed with colorectal cancer at 55, you’d get your first colonoscopy at 45.) The screening guidelines for more distant relatives of patients diagnosed before age 60, as well as for all family members of patients diagnosed at or after 60, are the same as for the general public.
Researchers from the University of Utah School of Medicine wanted to see how well these guidelines were working for relatives of patients who’d had any type of adenoma, not just the more dangerous advanced adenoma. And they had unique resources to draw upon—because Utah has an extensive genealogy database going back to the 1800s…plus a statewide cancer registry…plus comprehensive electronic medical records covering 85% of the state population. By linking these information sources, the researchers could determine the risk for colorectal cancer among immediate and distant relatives of people who’d had adenomas.
First, they searched for 50- to 80-year-old residents of the state who had a colonoscopy over a 14-year period and identified 43,189 people for whom colonoscopy revealed an adenoma. These patients were then matched to controls, meaning people of the same age and gender who also had colonoscopies but were not found to have adenomas.
Finally, the researchers used specially developed “kinship analysis” software to determine the magnitude of colorectal cancer risk—for first-degree relatives (parent, child, sibling)…second-degree relatives (half-sibling, aunt/uncle, niece/nephew, grandparent, grandchild)…and third-degree relatives (first cousin, great-grandparent, great-grandchild)—of patients who’d had adenomas. What they found…
• First-degree relatives of people with adenomas had a 35% greater risk for colorectal cancer compared with first-degree relatives of the controls.
• Second-degree relatives of people with adenomas had a 15% greater risk for colorectal cancer…and third-degree relatives had 6% greater risk. This was surprising, as the researchers didn’t expect the risk to be greater for distant relatives in multiple generations.
The biggest surprise—and biggest concern: Approximately 10% of first-degree relatives of patients with adenomas developed colorectal cancer at ages younger than those currently recommended to start colonoscopy screening based on family history. The researchers said that this raises the issue of whether more aggressive screening (such as starting at age 40) is indicated for close relatives of patients diagnosed with adenomas before age 60 and for those diagnosed with advanced adenomas at or above age 60.
Self-defense: If you have a relative whose colonoscopy revealed an adenoma, you are at increased risk for colorectal cancer. This type of cancer generally grows slowly, but it’s important to catch it at its earliest stages to maximize the odds for recovery. Show this article to your doctor and discuss getting screened—and urge your loved ones to do so as well—even if you or they think it’s “too soon” to worry about colorectal cancer.
Source: N. Jewel Samadder, MD, assistant professor of medicine, department of gastroenterology, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City. His research was published in Cancer.
