One of the first questions parents ask when a child is diagnosed with cancer is “Will my other children get cancer?” A new study suggests that the answer to that question depends on whether a family history of cancer exists.

The study, led by Joshua Schiffman, MD, of the Huntsman Cancer Institute at the University of Utah in Salt Lake City, examined the family medical history of 4,482 children in whom cancer was diagnosed over a 43-year period to determine the cancer risk in their relatives.

The research team found that when any kind of cancer is diagnosed in children age 18 years or younger, the risk for childhood cancer in their parents, siblings, or children doubled compared with families with no childhood cancer. If the cancer diagnosis was made when the child was 4 years or younger, the risk for childhood cancer in close relatives increased almost four times.

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“No one had previously studied the question, so we simply told parents there was no evidence of increased risk to the other children,” said Schiffman. “Now we can give an evidence-based answer—the risk depends on your family history of cancer.”

This is the first study that uses the Utah Population Database (UPDB) to broadly examine the risk for all types of cancer in relatives of children with cancer. This unique resource at the University of Utah links genealogies and cancer registry data from Utah to medical records and vital records, including Utah death certificates. This data source reduces errors that could come if the family medical history data was self-reported.

The team also assessed known inherited genetic syndromes in adult relatives of pediatric cancer patients. They found cancers associated with Li-Fraumeni Syndrome (LFS) seemed to drive the increased risk to relatives in families with a history of cancer.

“Not all children’s cancers are hereditary,” said Schiffman. “But the numbers in this study suggest that the proportion of hereditary childhood cancers may be significantly higher than the 5% to 10% generally cited in adult hereditary cancers, and likely even more than 20%.

“LFS is one of the most devastating cancer syndromes,” said Schiffman. “It causes a variety of cancers in both children and adults. For people with LFS, the lifetime risk for developing cancer is 80% to 90%, but with increased and early screening for tumors, there’s early indication of a very high survival rate, perhaps even approaching 100%. In a previous study, LFS patients who did not receive early screening only had a 20% survival rate.”

Although childhood cancer rarely occurs in the population, based on their findings, the authors recommended collection of three generations of family medical history for all patients with newly diagnosed pediatric cancer and referral for genetic counseling for families with a history of early-onset cancers in children or adults. In addition, parents of children with a cancer diagnosis at younger than 5 years should be advised of the increased potential risk to their other children if there is a family history of cancer.