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Return to Doctors' Advice: Who's, How's, and Why's of Genetic Testing for Colorectal Cancer Overview

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Return to Doctors' Advice: Who's, How's, and Why's of Genetic Testing for Colorectal Cancer Overview

More on Doctors' Advice: Who's, How's, and Why's of Genetic Testing for Colorectal Cancer

Doctors' Advice: Who's, How's, and Why's of Genetic Testing for Colorectal Cancer

New York (Oct 1, 2011)

Discovering that you have a familial colorectal cancer syndrome can be difficult, but lifesaving, news. Although people who have inherited one of the mutations linked to these syndromes have a very high risk of developing colorectal and certain other cancers, doctors now have the tools to both closely monitor patients and to treat them when necessary.

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Doctors consider referring someone for genetic testing for a colorectal cancer syndrome when a patient has several relatives with colon cancer on the same side of the family within multiple generations, especially if one or more of the family members developed cancer at an early age (less than 50 years old). "That's a very big clue that there's a syndrome going on in a family," said Felice Schnoll-Sussman, M.D., a gastroenterologist and Director of Research at The Jay Monahan Center for Gastrointestnal Health at NewYork-Presbyterian/Weill Cornell Medical Center.

Felice H. Schnoll-Sussman, M.D.
Felice H. Schnoll-Sussman,
M.D.

Colorectal cancer due to an inherited gene abnormality is usually linked to one of two syndromes," said Fay Kastrinos, M.D., M.P.H., a gastroenterologist at NewYork-Presbyterian/Columbia University Medical Center and Director of the Hereditary Colorectal Cancer Prevention Center. "In familial adenomatous polyposis (FAP), patients have a strong family history of early onset colorectal cancer in the setting of having multiple polyps." Patients with FAP begin to develop adenoma type polyps at a very early age, and can develop hundreds to thousands of polyps throughout the colon. Screening for polyps with endoscopy begins at age 12, and many patients eventually undergo prophylactic colectomy (removal of the colon) to prevent colon cancer.

Fay Kastrinos, M.D., M.P.H.
Fay Kastrinos, M.D., M.P.H.

Lynch syndrome, also called hereditary non-polyposis colorectal cancer (HNPCC), the other inherited syndrome, is the most prevalent form of hereditary colon cancer, and accounts for up to 5% of all colon cancers, said Dr. Kastrinos. Patients with Lynch syndrome start forming polyps at a young age and the polyps grow very quickly, raising the risk of colon cancer. Patients with the abnormal genes associated with Lynch syndrome begin screening with colonoscopy at age 25, and have colonoscopies yearly.

The mutations that cause both of these syndromes are passed from one generation to the next, and a parent with an abnormal gene has a 50 percent chance of passing it on to his or her child.

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Genetic testing for the mutations that causes these syndromes is key to patients' long-term survival. "The main utility in having someone tested is to fine tune and tailor their management in terms of prevention, screening, and surveillance," said Dr. Kastrinos. "More importantly genetic testing results can be used to prevent cancer in family members who are also at increased risk."

Surveillance after a positive test for a colorectal cancer syndrome can include annual colonoscopies, screening for the other cancers associated with these syndromes, and prophylactic colectomy, Dr. Schnoll-Sussman said. "A practitioner taking care of these patients usually provides care for the entire family – their children, aunts, and uncles – and builds lifelong relationships with them."

Genetic counselors are involved in the testing from the start, because of the impact this information can have on a family. "The whole emotional overlay with genetic testing is incredibly difficult," said Dr. Schnoll-Sussman. Parents who transmit one of these genes to their children often feel a great deal of guilt. "We battle that with the truth," she said. "Yes, you have this gene, and you will require surveillance and possibly surgery. Our goal is to provide diligent surveillance and prophylactic care so that cancer is prevented whenever possible, and if cancer does develop, to detect it early and treat it effectively. With the appropriate care, most people with a hereditary colon cancer syndrome can lead long, normal lives."

In families where one person receives a positive test result, "a big dilemma is having other family members who are at risk but unaffected by cancer come in for testing," said Dr. Kastrinos. "The duty lies with the patient to go back and communicate the results with their family members, and communication is extremely important in these cases." One study shows that for every one person who tests positive for the gene up to eight people in their families may be at risk – but that less than half of those at risk come in for testing. This may change, she said, "because we're moving away from the stigma associated with genetic testing. Many people are beginning to see that undergoing genetic testing can be a proactive measure in preventing colon cancer."

Fay Kastrinos, M.D., M.P.H. is the Director of the Hereditary Colorectal Cancer Prevention Center at NewYork-Presbyterian/Columbia University Medical Center and an Assistant Professor in Clinical Medicine at Columbia University College of Physicians and Surgeons.

Felice H. Schnoll-Sussman, M.D., is the Director of Research at The Jay Monahan Center for Gastrointestinal Health at NewYork-Presbyterian/Weill Cornell Medical Center and an Assistant Professor of Medicine at the Weill Cornell Medical College.

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