Colon cancer currently represents eight percent of all cancer deaths in the United States. While the majority of colon cancer is sporadic, or nonhereditary, colon cancer can also be hereditary.
The most common inherited colon cancer syndrome is hereditary nonpolyposis colorectal cancer, better known as Lynch syndrome. Lynch syndrome increases an individual's risk of cancer in the colon, rectum, stomach, small intestine, liver, bile ducts, kidneys, brain and skin.
Women with Lynch syndrome have an increased risk for gynecological cancers, such as ovarian and uterine (endometrial) cancer.
According to the National Institutes of Health, Lynch syndrome accounts for three to five percent of colon cancers.
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There are several factors that may indicate Lynch syndrome, such as a young age of the patient at diagnosis and the prevalence of colon or endometrial cancer in multiple family members or generations of family.
The majority of sporadic colon cancer cases occur in those older than 50. If a patient or a family member has experienced polyps (precancerous lesions in the colon), colon cancer or endometrial cancer before age 50, it could be an indication of Lynch syndrome. In fact, cancer at an early age is the strongest red flag there may be a hereditary link.
Likewise, if a first or second degree relative has been diagnosed with colon or endometrial cancer before the age of 50, or three family members spanning two generations experience colon or endometrial cancer at any age, the cancer could be hereditary and Lynch syndrome could be present.
In a person with Lynch syndrome, they have a 70-80 percent chance of developing colon or endometrial cancer by the age of 70.
While discussion about colon cancer and polyps may not be a comfortable conversation to have with your family members, understanding your family's history is important information that is incredibly helpful when it comes to colon cancer prevention.
For individuals who meet the criteria discussed above, genetic testing may be recommended to help determine their risk for cancer. Although Lynch syndrome is not new, in more recent years testing has become more widely available and accessible.
Genetic testing is done through a blood test that is virtually painless. In some cases, the testing is covered by insurance.
Identifying genetic factors that increase an individual's risk for colon and endometrial cancer often results in a more aggressive screening strategy to help prevent cancers from developing or diagnose them at earlier stages when they are more treatable.
Most sporadic colon cancers occur on the left side of the colon therefore patients may experience symptoms such as a change in stool caliber or rectal bleeding. Hereditary colon cancer caused by Lynch syndrome most commonly occurs on the right side of the colon and may have no symptoms until they are at an advanced stage. Therefore, knowing your risk and developing a more aggressive screening strategy is critical to preventing cancer at an early age.
For patients with a family history of colon cancer or precancerous polyps, screening is typically recommended beginning at age 40, or 10 years prior to the age of earliest colorectal cancer diagnosed in the family, whichever is younger.
Patients identified with Lynch syndrome should then undergo annual gynecological examinations and colonoscopy every one to two years.
In patients who are considered average risk without any family history, the American Cancer Society recommends colon cancer screenings beginning at age 50 for both men and women and age 45 for black males.
Colon cancer is a preventable cancer.
Talk with your doctor about your family history and develop a screening plan that is right for you.