Family Matters: Colorectal Cancer and Heredity

Choose your ancestors wisely, the saying goes.

Oh, if only we could, especially when it comes to our health.

“Mostly there are three factors that bring on disease,” explains Chandan Gupta, MD, a family medicine practitioner at the Monroe Medical Center. “One is your genetics, the other is the lifestyle you have, and the third is the environment.”

Colorectal cancer is a prime example, says Dr. Gupta. The American Cancer Society (ACS) reports that up to one out of five people diagnosed with colorectal cancer has a family history of the disease.

Dr. Gupta advises that you take time to study your family’s health history and determine if one of the following has shown up among your relatives.

Family History of Colorectal Cancer or Polyps

If your family has a history of colorectal cancer or adenomatous polyps (a type of polyp that can become cancerous), your risk increases. The risk is even higher if a relative was diagnosed with colorectal cancer when they were younger than 45, or if more than one first-degree relative (a parent, child or sibling) is affected.

If you have a first-degree relative who has had colorectal cancer, talk to your doctor or health care provider. You may be a candidate for screening before the usual recommended age of 50.

Inherited Syndromes

About five to 10 percent of people who develop colorectal cancer have gene defects that can lead to the disease, according to the ACS.Family Matters Colorectal Cancer and Heredity - In Content

The most common genetic syndromes linked with colorectal cancer are familial adenomatous polyposis (FAP) and Lynch syndrome (hereditary non-polyposis colorectal cancer, or HNPCC):

  • Familial adenomatous polyposis (FAP): About one percent of all colorectal cancers are due to FAP. In the most common type, hundreds or even thousands of polyps develop in a person’s colon and rectum, usually when the person is in her teens or early adulthood. Cancer usually develops in one or more of these polyps as early as age 20. By age 40, almost all people with this disorder will have developed colon cancer, if the colon isn’t removed first to prevent it. People with FAP are also at increased risk for cancers of the stomach, small intestines and some other organs.

    Because FAP starts at a young age, screening often begins in childhood. For children at risk, genetic testing can be of value to spare the child from having annual screenings (for example, sigmoidoscopy or colonoscopy) if the mutation is not present.

    In attenuated FAP, a subtype of this disorder, patients have fewer polyps (less than 100), and colorectal cancer tends to occur at a later age.

    Gardner syndrome is another type of FAP that also includes non-cancerous tumors of the skin, soft tissue and bones.

  • Lynch syndrome (hereditary non-polyposis colon cancer, or HNPCC): Lynch syndrome accounts for about two to four percent of all colorectal cancers. In most cases, it is caused by a defect in the genes that normally help repair DNA damage.

    People with Lynch syndrome develop cancers when they are young, although not as young as in FAP. They also may have polyps, but they tend to only have a few, not hundreds as in FAP. The lifetime risk of colorectal cancer in people with this condition may be as high as 80 percent, according to the ACS.

    Women with Lynch syndrome also have a very high risk of developing cancer of the endometrium (the uterine lining).Also linked to Lynch syndrome are cancers of the ovary, stomach, small intestine, pancreas, kidney, brain, ureters (tubes that carry urine from the kidneys to the bladder) and bile duct.

    The average age for colorectal cancer to be diagnosed in someone with Lynch syndrome is 45, as compared with the average age of 72 for a new diagnosis of colorectal cancer in the general population.

Race and Ethnicity

African Americans have the highest colorectal cancer incidence and mortality rates of all racial groups in the U.S., according to the ACS. The reasons for this are not yet known. In addition, Ashkenazi Jews (Jews of Eastern European descent) have one of the highest risks of any ethnic group in the world. Researchers have found several gene mutations causing the increased risk in this group. The most common of these, called the I1307K APC mutation, is present in about six percent of American Jews, and is associated with a 10 to 20 percent risk of colorectal cancer (slightly more than double the risk in the general population).

Should I Be Tested?

This is an important conversation to have with your doctor. Dr. Gupta advises that you come to the visit prepared with as much detail about your family health history as possible. “There are certain warning signs we can get from family history,” she says. “If the same disease keeps repeating among many family members, that is something to be concerned about.” Your doctor will help you determine whether you and your family members should begin testing, and when. “The sooner the better” is Dr. Gupta’s advice, especially if you are concerned your children may be affected.

Take time to study your family’s health history

This allows you to anticipate your risk of developing this disease and plan ahead to prevent or treat it as early as possible.

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