Genetic counselors can shed light on disease
Colon cancer is one of the most common types of cancer. Most colon cancers are sporadic: that is, they are not inherited and cannot be passed to your children. Although the cause is usually unknown, sporadic cancers may occur due to environmental exposures. In other cases, mistakes (mutations) can occur in genes by chance when a cell divides. Since these mutations occur only in the cancer cells, they cannot be passed on to one's children.
Sometimes, several members of a family will develop colon cancer. In these cases, cancer is occurring more often than would be expected by chance, yet does not appear to be clearly hereditary (passed from parent to child). Very little is known about the causes of cancer in these families. It is possible that interactions are occurring between genes and the environment or among several genes.
About 5 to 10 percent of colon cancers are believed to be hereditary. When individuals are at risk for hereditary cancer, this means that they have inherited a gene with a mutation in it, which makes them more prone to developing cancer. Individuals who inherit a mutation in a cancer susceptibility gene have a much greater chance of developing cancer. However, not everyone with a cancer susceptibility gene mutation will develop cancer.
The Importance of Family History
“One of the most well established risk factors for developing colorectal cancer is family history. It is important that patients speak with their family members about their history of cancer and convey this information to their healthcare providers,” says Brandie Leach, a genetic counselor who works with patients at Cleveland Clinic’s Digestive Disease Institute. “Family history factors that may be concerning include: multiple members on one side of the family diagnosed with colorectal cancer; individuals diagnosed with colorectal cancer prior to age 50; family members with greater than 10 colon polyps; or a family history of a hereditary colorectal cancer syndrome.”
For patients with these types of family histories, genetic counseling and/or genetic testing may be available to help identify who is at risk to develop colorectal cancer, Ms. Leach says. This could lead to more intensive screening that can help reduce the risk of developing a cancer. “The placement of genetic counseling services within the Digestive Disease Institute has helped to create greater access to genetic services for patients with, or at risk for, hereditary colorectal cancer,” she says. “This helps to ensure that patients are receiving comprehensive and multidisciplinary care, and that the physicians are incorporating genetic and family history information into their patient care.”
For more information about genetic counseling at the Center for Personalized Genetic Healthcare at Cleveland Clinic’s Genomic Medicine Institute, please call 216.445.5686.
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