Genetic testing could hold answers for colon cancer survival

The Human Genome Project was a 13-year-long, publicly funded project initiated in 1990 to determine the entire DNA sequence of the human genome. While the Project was declared complete in April, 2003 the advancements of genetic testing continues to evolve.

The sequencing of the human genome holds benefits for many fields such as forensic science, biofuels and agriculture but one of the most powerful benefits remain in the identification of mutations linked to different forms of cancer; Colon cancer, in particular.

Colon cancer is the second-leading cause of cancer-related deaths in the United States and the third most common cancer. It kills more than 50,000 people annually and impacts men and women almost equally.

The good news is colon cancer rates are generally falling, thanks to better screening and improved treatments. According to the American Cancer Society, between 1990 and 2015, colorectal cancer declined 47 percent among men and 44 percent among women.

One of the newest weapons in the medical arsenal for fighting colon cancer is genetic testing.

According to research published in Gastroenterology, colorectal cancer has one of the largest proportions of familial cases. The report says, based on kindred and twin studies as many as 30 percent of colorectal cancer cases are an inherited form of the disease.

“When individuals have an underlying predisposition for cancer, genetic testing might affect their treatment and screening plans, their risk for additional cancers and cancer risks for other family members,” explains Kimberly Brussow, certified genetic counselor at The University of Arizona Cancer Center at Dignity Health St. Joseph’s Hospital and Medical Center.

A doctor may suggest starting screening at a younger age, more frequent screening and using colonoscopy instead of other tests in cases where patients have a close family member who developed colorectal cancer at a young age or who have multiple close family members with colorectal cancer, notes the CDC. In some cases, your doctor may recommend genetic counseling and a genetic counselor could prescribe genetic testing based on your family health history.

“When we see there is a family history of cancer, we certainly can do genetic testing to see if it is a hereditary cancer type or not.” Brussow says. The testing has changed dramatically. As recently as 10 years ago, Brussow says, it was only possible to test for five genes at a time and the testing was expensive.

Today, Brussow says they test up to 25 different colon cancer genes and up to a total of 80 different cancer genes at once and the cost of the testing has declined dramatically.

The most common hereditary colon cancer syndrome, Lynch Syndrome, is responsible for about 3 percent of colorectal cancers, reports the CDC. But individuals who have Lynch Syndrome are also at increased risk for uterine, ovarian, and other cancers.

When deciding whether genetic testing is appropriate for a specific patient, Brussow says she considers three factors:

• If there are multiple cancers in a family — usually three or more.
• If someone is young at their age of diagnosis — typically under age 50.
• Or, if there are rare cancers in the family.

If you think you might fall into one or more of those categories or if you are concerned about your personal or family health history of colorectal cancer, you might want to schedule a consultation with experts at The University of Arizona Cancer Center at Dignity Health St. Joseph’s Hospital and Medical Center.

 

Lifestyle factors are still primary contributors of increased colon cancer risk. The CDC advises the most critical concerns include a lack of regular physical activity, a diet low in fruit and vegetables, a low-fiber and high-fat diet, obesity, alcohol consumption and tobacco use.

To understand your risk for colon cancer, take our online colon cancer health risk assessment