Genetic Testing & Risk Factors For Colon Cancer

Aging increases a person's risk for developing cancer, but colorectal cancer is being diagnosed in people of all ages. In fact, colon and rectal cancer has been declining in older adults in recent decades and rising sharply in adults as young as 20.

In this article, you will learn about risk factors for colorectal cancer, why adults in their 40s should be concerned about their colon cancer risk, when to consider genetic testing for colon cancer and when to get your colon cancer screening.

Key Takeaways: Colon Cancer Risk & Genetic Testing

• Genetics, diabetes, smoking, a previous history of other cancers and a history of ulcerative colitis or Crohn's disease are risk factors for colorectal cancer.
• If you or a close relative has had a history of cancer, you may want to consider genetic counseling for colon cancer.
• Colorectal cancer is diagnosed after cancerous cells are found in the large intestine, or colon.

Do I Have Risk Factors For Colorectal Cancer?

Certain people may be at a greater risk for developing colorectal cancer. While age (typically over age 50) and family history of colorectal cancer or polyps are risk factors, other things can put you at increased risk of colorectal cancer:

• Genetic conditions that might make you more prone to having colon cancer
• Previous history of other cancers, including ovarian, uterine, or breast cancer
• Previous history of ulcerative colitis or Crohn's disease
• Diabetes
• Being a current or former smoker

Should I Worry About Colon Cancer Before Age 50?

Experts say people born in 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer at, say, age 40, compared to someone born in 1950 at age 40.The American Cancer Society estimates about 158,850 new cases of colon and rectal cancers will be diagnosed in Americans this year. Because doctors don't often consider colon cancer in young adults, these patients may not get the needed cancer treatment until the colon cancer has progressed to a later stage. Several reasons have been offered for this increase in colon and rectal cancers among younger adults, including rising obesity and poor diets.

But a major factor for having a higher risk of colon cancer appears to be genetics, or a family history of cancer.

Has A Family Member Had Colorectal Cancer?

As many as one in five people who develop colorectal cancer have other family members who have had it.

"Risk is higher with a cancer family history, especially if a relative was diagnosed with cancer when younger than 45 or if more than one relative was affected," said Morgan Dally, MS, CGC, LGC, Cancer Genetic Counselor at the Franciscan Health Cancer Center. "Precancerous polyps in a family member also is linked to higher risk."

Although researchers are not yet sure how big a role your genes may play in colorectal cancer, you might have an increased risk if a close family member has the disease, according to a report in the New England Journal of Medicine. About 20 percent of all patients have a family history of the disease. Your risk is increased if a first-degree relative (i.e., parents who had cancer before age 60, or a sister or brother) has had colon cancer.

Is There a Genetic Link To Colorectal Cancer?

The American Cancer Society reports that about 5 to 10 percent of cancers are hereditary, caused by underlying gene changes (mutations) that can cause family cancer syndromes. The most common inherited syndromes linked with colorectal cancers are familial adenomatous polyposis (or FAP) and Lynch syndrome, but other rarer syndromes also can increase colon and rectal cancer risk, according to Dally.

"Identifying families with these hereditary risks is important since colorectal cancer may develop early in these people and also may contribute to other types of cancer,” Dally said. “Early identification means doctors can recommend screening and other preventive measures before the cancer progresses."

Dally recommends that if you have a family history of polyps, colorectal cancer or an inherited syndrome such as FAP or Lynch syndrome, talk with your doctor about when you should begin colon cancer screening. Also, if you personally have had polyps or colorectal cancer, please tell your close relatives so they can follow-up with their physicians. You might also consider genetic testing to assess your risk of colon cancer risk or developing other cancers in the future.

How Does Genetic Testing For Colon Cancer Work?

Genetic testing is typically recommended for people with a personal and/or family history suggestive of a hereditary cancer condition. It is important to know that having a family member with cancer does not automatically mean that you are in a high-risk family.

If you or a close relative have had any of the following, you may want to consider genetic counseling for colon cancer:

• Two or more close relatives on the same side of the family with cancer, especially of the same type
• Cancer at a young age (under age 50)
• More than one diagnosis of cancer in the same individual, such as breast and ovarian, or colon and uterine cancer
• Rare cancers, such as male breast cancer
• One or more relatives with a known hereditary cancer gene mutation

Cancer genetic testing is the process of collecting your detailed personal and family history, assessing your personal risk and discussing your genetic testing options. Genetic tests are tests of blood and other tissue used to identify genetic disorders and can help obtain a more precise estimate of your cancer risk. Although a cancer risk assessment can be provided without genetic testing, in some cases testing may help you and your physician make important decisions about your medical care.

How Is Colorectal Cancer Diagnosed?

Colorectal cancer is diagnosed after cancerous cells, often beginning as precancerous polyps, are found in the large intestine, or colon. These polyps are extremely common, and their incidence increases as people get older. These polyps can be tiny and cause no symptoms, so regular screening is suggested to remove polyps before they become cancerous. Certain types can become cancerous as they grow, and that is why screening is important for adults.

Polyps usually are diagnosed for possibility of colorectal cancer by looking at the colon lining during a sigmoidoscopy or colonoscopy. A sigmoidoscopy lets the physician to examine the last six to eight inches of the colon, usually in an office setting. For a colonoscopy, the physician uses a flexible endoscope to examine the entire colon. Polyps usually can be removed during the procedure.

If diagnosed and treated at an early stage, colon cancer patients are more likely to have good outcomes.