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Parents planning a family often ask: what causes pediatric cancer? This question is especially important for those considering in vitro fertilization (IVF) or preimplantation genetic testing (PGT) to ensure a healthy future child. Pediatric cancer refers to cancers occurring in children and adolescents (typically under age 19). It is relatively rare, affecting about 400,000 children globally each year, with roughly 15,000 new cases annually in the United States (What Causes Cancer in Children). Pediatric cancers can arise in almost any organ, though the most common types in children involve the blood (leukemias), lymphatic system, and central nervous system (What Causes Cancer in Children). Below, we explore the known causes of pediatric cancer, from genetic mutations to chance events, and how modern genome screening can help prospective parents assess and mitigate risk.

Genetic vs. Sporadic Causes of Childhood Cancer

The development of cancer in children involves a complex interplay of genetic and environmental factors. In most pediatric cancer cases, there is no clear inherited cause – the cancer appears to occur de novo, or by chance. In fact, approximately 80–90% of pediatric cancers arise sporadically, without a familial genetic link. Only a minority (roughly 8–10% of cases) can be traced to a genetic mutation that the child was born with (a germline mutation) which predisposed them to cancer (What Causes Cancer in Children). In other words, most childhood cancers are not inherited from a parent, though a small fraction are related to genetic predispositions present from birth.

Even when a child is born with a cancer-predisposing mutation, it may not always come from the parents’ DNA. Some mutations associated with pediatric cancer occur de novo, meaning they arose spontaneously in the egg, sperm, or early embryo. For example, Li-Fraumeni syndrome is a rare hereditary condition caused by changes in the TP53 gene that gives a very high lifetime cancer risk. Li-Fraumeni is typically inherited from a parent, but in some cases the TP53 mutation can appear spontaneously in an embryo (de novo). This illustrates that while hereditary cancer syndromes do exist, they are uncommon. Overall, fewer than 1 in 10 children with cancer have an identifiable inherited genetic cause for their disease (What Causes Cancer in Children).

How Whole-Genome Screening Helps Prospective Parents

Given that most pediatric cancers are not inherited, there is no guaranteed way to prevent all childhood cancers. However, understanding genetic risk factors can help prospective parents make informed decisions. Preimplantation Genetic Testing (PGT) during IVF allows parents with known hereditary mutations to screen embryos and avoid passing on a cancer predisposition. If a parent carries a known cancer-related gene variant, each child has about a 50% chance of inheriting it. Many families in this situation choose IVF with PGT so they can select an embryo that does not carry the harmful variant. This approach is commonly done through PGT-M (PGT for monogenic disease), which tests for a specific mutation known to run in the family. A limitation of traditional PGT-M, though, is that it can only look for the particular variant you know about – the parents must have prior genetic testing to identify that mutation.

Modern advances now allow for broader genome screening of embryos beyond single-gene tests. Such comprehensive screening, essentially an expanded form of PGT, gives would-be parents a more complete picture of their future child’s genetic risk profile. Orchid’s embryo report is an example of a report that highlights whether an embryo has inherited any high-risk variants for pediatric cancers or other conditions, so parents can make informed choices before implantation. Even if you have no known family history of cancer, embryo genome screening can detect new (de novo) genetic errors that occurred by chance (What Causes Cancer in Children) – providing an extra layer of reassurance.