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In children, the single most common cancer diagnosis is leukemia. Leukemia – a cancer of the blood-forming cells in bone marrow – accounts for about 28% of all pediatric cancer cases (Overview of Childhood Cancer - Children's Health Issues - Merck Manual Consumer Version). In other words, nearly one in three childhood cancers is a leukemia (Leukemia in Children | American Cancer Society), most often acute lymphoblastic leukemia (ALL). Each year, only a few thousand children in the United States are diagnosed with leukemia, making it the leading childhood cancer by incidence but still relatively rare. (By comparison, brain and central nervous system tumors are the second most common group, about 25% of cases, followed by lymphomas at ~12%) Encouragingly, advances in treatment have greatly improved outcomes – the five-year survival rate for childhood ALL now exceeds 90% (Cancer in Children and Adolescents - NCI).

Understanding Pediatric Cancer Risk

For any parent, hearing about pediatric cancer can be frightening. The good news is that childhood cancers are uncommon, and most have no identifiable cause or risk factor. Unlike many adult cancers, which can be linked to lifestyle or environmental exposures, cancers in kids often arise from random genetic mutations during growth. While all cancer is genetic in origin, only a small fraction of pediatric cancers are due to inherited mutations. Researchers estimate roughly 10–12% of childhood cancers are caused by hereditary genetic variants passed down in families (Embryo Screening and Hereditary Cancer). This means the majority of cases occur sporadically, without a family history or anything parents did “wrong.” For example, if one child in a family develops leukemia, their siblings are generally not at higher risk of getting it (Childhood leukemia: 5 things parents should know | MD Anderson Cancer Center) unless a specific hereditary syndrome is involved. Understanding this can be reassuring: most families will not face pediatric cancer, and even those who do usually could not have prevented it.

That said, certain inherited gene mutations can predispose a child to cancer. Kids with genetic conditions like Li-Fraumeni syndrome or hereditary retinoblastoma have a much higher chance of developing cancer early in life. Identifying such risks ahead of time can help families take precautions and work closely with doctors for early detection. This is where proactive genetic screening becomes important in family planning.

How Genetic Testing Can Help

Prospective parents considering in vitro fertilization (IVF) often have the option of preimplantation genetic testing (PGT) to screen embryos for health risks before pregnancy. If a parent carries a known hereditary cancer gene, there is a 50% chance it could be passed to their child (How can Orchid tell me about an embryo’s future risk for cancer?). Many families in this situation choose to undergo IVF and have their embryos genetically tested so they can select an embryo without that high-risk mutation. For instance, Orchid’s educational guides describe two sisters who survived hereditary retinoblastoma (a pediatric eye cancer) and used embryo screening to avoid passing the retinoblastoma gene (RB1) to their children (Embryo Screening and Hereditary Cancer). By leveraging PGT, these parents dramatically reduced the likelihood that their babies would face the same cancer.