March 5, 2007
A University of Michigan Health Minute update on important health issues.
Colon cancer risk: It's often all in the family
U-M expert says counseling, screening for genetic predisposition to colon cancer can save lives
ANN ARBOR, MI – Forty-one-year-old Amenia Lauth has a family history of colon cancer. Her grandfather and uncle, both of whom developed colon cancer at a young age, succumbed to the disease, and several other relatives had precancerous polyps in their colon.
After a colonoscopy revealed that Lauth had thousands of polyps lining her colon, doctors at the University of Michigan Health System recognized that she had familial adenomatous polyposis, a condition with a high risk of colon cancer. Because of her family history, Lauth wondered if her children, too, were genetically predisposed to colon cancer. Fortunately, genetic screening and counseling found that none of her three children were carriers of the familial adenomatous polyposis gene that caused her polyps.
“I felt a great deal of relief after they were screened because it meant that they wouldn’t have to go through what I had gone through,” says Lauth, who had her colon removed following her diagnosis to prevent colon cancer from occurring.
Since about 10 percent of all colon cancers have a genetic component to them, experts at the University of Michigan Comprehensive Cancer Center recommend that people with a strong family history of colon cancer get genetic counseling and early screening, like Lauth and her children, to know their risks.
“Colon cancer is one of the most common cancers in the United States, and the good news is that it’s largely preventable with early screening,” says Stephen B. Gruber, M.D., Ph.D., director of the cancer genetics clinics at the U-M Cancer Center, and associate professor of internal medicine at the U-M Medical School.
The American Cancer Society estimates that some 150,000 new cases of colon cancer will be diagnosed in 2007, and more than 50,000 deaths from colorectal cancer will occur.
Although most cancers are not "inherited," some families are particularly susceptible to cancer and may benefit from early detection or other risk reduction strategies. Genetic counseling and screening can help to identify two common conditions associated with familial colon cancer risk: familial adenomatous polyposis, which caused colon cancer in Lauth’s family, or Lynch Syndrome, which usually causes cancer to develop either in the colon or the uterus.
“The best way to recognize Lynch Syndrome is to look at the patient’s family history to see if three or more family member have been diagnosed with colon cancer, and if any have been diagnosed before the age of 50,” notes Gruber. “Young onset colon cancer is one of the clues to inherited susceptibility for cancer.”
People concerned about a family history of cancer, or those who have been diagnosed with colon cancer before age 50, should talk to their doctor about the possible benefits of genetic counseling. In fact, Gruber encourages any patient with cancer who has two or more family members with colon cancer to consider genetic counseling.
Genetic counseling – available for all types of cancer including breast cancer, ovarian cancer, uterine cancer, and childhood cancers – typically involves an overview of cancer genetics, a history and physical examination to look for signs and symptoms of familial cancer, and individualized counseling regarding strategies of how to lower the risk of cancer.
And for people who are genetically predisposed to colon cancer, early screening methods, such as colonoscopy, can be a life-saver.
“Colonoscopy saves lives by allowing us to detect precancerous lesions and even early cancers at a time when they are relatively easy to treat,” say Gruber. “For people who are at an increased risk of cancer, those with an inherited susceptibility to cancer, we begin screening with colonoscopy at an early age – as early as age 20 for Lynch Syndrome and even in the teenage years for familial adenomatous polyposis.”
Regardless of family history, symptoms or lifestyle choices, everyone is at risk for colorectal cancer and should be regularly screened every 10 years after the age of 50, since many people often do not show any symptoms of colon cancer until it's too late.
Researchers at the U-M Cancer Center, too, are making great strides in developing new strategies for reducing the risk of colon cancer.
Using a colon cancer registry, Gruber and his colleagues are studying the people and families that are at an increased risk for developing colon cancer, and they also plan to launch a new study using computer simulated models to estimate a person’s risk of developing colon cancer. These study models, Gruber says, will help to determine how frequently a person should get a colonoscopy based on their family history, the number of people in their family with cancer and the ages at which those family members were diagnosed.
For more information, call the Cancer AnswerLine at 800-865-1125 or visit these Web sites:
U-M Cancer Center: Cancer Genetics Clinic
U-M Cancer Center: Colon cancer information guide
U-M colonoscopy screening
National Human Genome Research Institute
Centers for Disease Control & Prevention: Colorectal cancer
National Cancer Institute: Colon and rectal cancer
Written by Krista Hopson
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