Should Children Be Tested for Hereditary Cancer Syndromes?

A woman with Lynch syndrome discusses testing young people for hereditary cancer syndromes and emphasizes the importance of speaking with a genetic counselor.

My son loves classic rock, has thick, dark curly hair, a wicked sense of humor, and is one of the most magnetic men I know. He has so much in common with the uncle he has never known: his Uncle Jimmy, my brother who died young from colon cancer due to Lynch syndrome.

Chances are you have never heard of Lynch syndrome. Many have not, including most medical professionals, but it is the most common inherited form of hereditary cancer and affects approximately 1 in 279 individuals, or 1.2 million people in the United States. According to the National Cancer Institute, "One copy of a mutated gene from one parent can cause the genetic condition. It is an autosomal dominant syndrome and can be passed down from parent to child. A child who has a parent with the mutated gene has a 50% chance of inheriting that mutated gene. Men and women are equally likely to have these mutations and sons and daughters are equally likely to inherit them."

My son is almost 19, and I have been worried that he may have inherited Lynch syndrome from me for over a decade. He has not been genetically tested yet but is well aware that I have Lynch. When I first discovered Lynch syndrome, I wanted to test my son, who was only eight, but my genetic counselor advised against it.

It is generally not a good idea to genetically test minor children for hereditary cancer syndromes, such as Lynch syndrome or BRCA, unless their family medical history warrants it. One of the exceptions to this rule is in the case of familial adenomatous polyposis, or FAP. An individual may develop hundreds to thousands of polyps throughout their colon at a young age and develop colon cancer.

Lynch cancers are most likely to manifest during adulthood. According to my certified genetic counselor, if my son were to test positive for Lynch syndrome, it would be optimal to start his colonoscopy and other screening in his mid-20s. Screening should begin 10 years before the earliest Lynch cancer case in a family.

Lynch cancer in childhood is tragic but rare. I know of a few people through social media who have developed colon cancer during their teens, and a few have died from it, but the data suggests these cases are unusual.

One syndrome that often gets confused for Lynch syndrome is Constitutional mismatch repair deficiency (CMMRD). This rare disorder significantly increases the risk of developing one or more types of cancer in children and young adults. CMMRD occurs when a person inherits a Lynch gene from their father and a Lynch gene from their mother. This rare condition is associated with a high risk of early-onset cancers of the colon, rectum, brain and blood. It is not uncommon for someone with this rare syndrome to have café au lait spots.

While parents are right to be concerned for their child's welfare, there are multiple social, ethical and legal issues raised with the genetic testing of minor children. Genetic testing may benefit an entire family, but it may also affect a person's right to privacy.

Not all children can handle the emotional toll a Lynch syndrome diagnosis may bring. Genetically testing minor children for hereditary cancer syndromes before they reach adulthood may be more harmful than beneficial because this knowledge is not actionable in childhood. Suppose there is a strong family medical history of colon cancer developing when adults are in their 30s. In that case, doctors will most likely not begin offering colonoscopies to minor children within that family. According to a study published in American Family Physician, “Individuals who have a first-degree relative with colorectal cancer or advanced adenoma diagnosed before 60 years of age should start screening colonoscopy at 40 years of age or 10 years younger than the earliest diagnosis in their family, whichever comes first.”

Genetic testing may also have implications for a child's ability to obtain life insurance, disability insurance and long-term care insurance in adulthood. It is always best to speak with a certified genetic counselor before and after genetic testing.

I know my son is concerned about whether or not he has Lynch syndrome. I hope he is undergoing genetic testing when he graduates from college; however, I also want him to have the freedom of choice as to whether or not he tests. If he does have Lynch syndrome, he will have frequent colonoscopies and screening measures to maintain his health or catch cancer when it is most treatable.

What if my son tests negative for Lynch syndrome? I will be overwhelmed with joy and relief knowing this ends with me and not fret over him and his health and the possibility of him passing this on to his children.

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