What the research tells us about causes, risks, and prevention
September is Childhood Cancer Awareness Month! While I don’t treat pediatric cancer, I want to share research and insights that might help parents and families live healthier lives. My intention is not to scare or blame anyone, but to provide valuable information.
Whenever I talk about how it takes 8–10 years for cancers to develop, I often get questions about childhood cancers.
This is an important point to clarify. While most adult cancers take decades to form, childhood cancers follow different patterns. Many are influenced by exposures during very early development, sometimes even in the womb, when cells are dividing rapidly and are especially vulnerable. This means the timeline for cancer to appear can be much shorter in children than in adults.
Scientists often describe these as “critical windows of development.” During pregnancy, infancy, and early childhood, cells are multiplying and differentiating at extraordinary speed to build organs, tissues, and the immune system. At these stages, DNA repair mechanisms and detoxification systems are still immature. A toxic exposure, hormonal disruption, or nutrient deficiency in these windows can have far greater impact than the same exposure later in life, because it can permanently alter how tissues grow, how genes are expressed, and how resilient the immune system becomes.
That said, cancer in children is still relatively uncommon. In the United States, fewer than 1 in 300 children will be diagnosed with cancer before the age of 20.
The most common childhood cancer is acute lymphoblastic leukemia (ALL), which accounts for roughly 25% of all cases.
Survival rates have improved dramatically in recent decades thanks to advances in cancer care. Today, the overall five-year survival rate for childhood cancers is over 85% in the U.S.—a remarkable improvement compared to the 1970s, when fewer than half of children survived.
Still, the diagnosis is always difficult for families. There are many emotional and physical challenges, and long-term concerns about treatment side effects, fertility, and late health effects. The progress in survival offers hope, but we also need more research: finding gentler and more targeted treatments and understanding the causes and risk factors that might help us prevent childhood cancers in the first place.
Many parents are often told that the cause of their child’s cancer is “unknown.” But the truth is that only about 5–10% of childhood cancers can be traced to inherited genetic mutations.
Of course, it is never a parent’s “fault” if their child develops cancer, but it’s also not entirely random. We have a lot of research that shows that environmental exposures can contribute to cancer risk.
It’s so important for parents to be educated on these topics. If we believe everything is purely chance, we limit our ability to protect our children and take proactive steps. Awareness of environmental drivers doesn’t create blame, but rather gives families tools to reduce risks where possible and to foster healthier conditions for their children.
A few things to know:
- When we improve our health, we improve the health of our children.
A child’s risk of disease begins before birth. Studies consistently show that maternal health, nutrition, hormonal balance, and stress, shapes fetal development. For example, the “Developmental Origins of Health and Disease” (DOHaD) hypothesis has shown that poor maternal nutrition can alter how a child’s metabolism and immune system develop, increasing susceptibility to chronic disease and cancer later in life.
This doesn’t mean parents must be perfect, but every step toward healthier living before and during pregnancy (balanced diet, reduced toxin exposure, stress management) provides a better foundation for a child.
- Maternal stress is linked to an increased risk of childhood cancer.
High stress in pregnancy has been linked to increased cancer risk in children. A large population-based cohort study across Denmark and Sweden followed over six million children (Li et al., 2012). Researchers found that severe prenatal stress, particularly the loss of a child or spouse, was associated with higher risks of non-Hodgkin lymphoma and hepatic cancer.
Stress hormones like cortisol and adrenaline can cross the placenta, influencing fetal immune system development. Chronic maternal stress may also dysregulate thyroid function, nutrient absorption, and detoxification—all key during critical windows of growth. Reducing chronic stress during pregnancy may therefore act as an indirect cancer prevention strategy.
- Maternal hypothyroidism is linked to an increased risk of childhood cancer.
Thyroid hormones are essential for brain and nervous system development, and during pregnancy a mother’s thyroid output increases by about 50% to support the baby’s growth. If this extra demand isn’t met, because of hypothyroidism or autoimmune thyroid disease, the child’s development can be affected. Without enough, tissues may grow abnormally or remain in a more “immature” state, which can increase susceptibility to cancer.
A Finnish case–control study of over 2,000 childhood cancer patients found that maternal hypothyroidism during pregnancy was associated with a 41% increased risk of childhood cancers overall. The link was especially strong for lymphomas, where risk was more than tripled. These findings suggest that insufficient thyroid hormone availability during fetal development may make certain tissues more vulnerable to cancer later in childhood.
- In utero exposure to estrogens and xenoestrogens raises the risk of childhood cancers.
Research has shown that prenatal exposure to xenoestrogens is associated with a higher risk of certain childhood cancers. The developing fetus is especially sensitive because cell division is rapid and hormonal cues act like “instructions” for building organs and tissues. When those signals are distorted, the result can be abnormal growth patterns or changes in gene expression that predispose to cancer later in childhood.
For example, diethylstilbestrol (DES), a synthetic estrogen prescribed to pregnant women from the 1940s to the 1970s, was later found to cause rare vaginal cancers, reproductive problems, and fertility issues in daughters exposed in utero.
Today, chemicals like BPA (bisphenol A), phthalates, parabens, and pesticide residues are common in plastics, personal care products, and food packaging. Studies confirm that these compounds can cross the placenta and may become even more potent once metabolized in the fetal environment.
- Radiation exposure is linked to higher rates of childhood leukemia.
Radiation is one of the best-established environmental risk factors for childhood leukemia. In the mid-20th century, studies of prenatal X-rays showed that children exposed in the womb had about a 40% higher risk of developing leukemia compared to unexposed children. More recent research has extended these findings: a large UK cohort study of children who had CT scans found that those receiving cumulative doses of ionizing radiation equivalent to just two or three scans had a significantly higher (triple) the risk of both leukemia and brain tumors (Pearce et al., 2012).
Because of this, families should ask informed questions: Is this scan essential? Are there safer alternatives, like ultrasound? Can the lowest effective dose be used? For pregnant women, this awareness is even more critical, because radiation exposure in utero is one of the most clearly documented risk factors for childhood leukemia.
- Maternal pesticide exposure preconception is linked to increased risk of childhood brain cancers.
Pesticide exposure before and during pregnancy has been repeatedly linked to higher risks of childhood cancers, especially brain tumors. A case–control study of over 10 pediatric oncology centers across Australia found that professional pest control treatments in the home during the year before pregnancy carried a statistically significant 54% increased risk of childhood brain tumors in offspring
Why does timing matter so much? The months before conception and early pregnancy are considered critical windows of vulnerability. A mother’s body is preparing the genetic and epigenetic blueprint that will be passed to her child. During this period, chemical exposures can alter DNA expression, disrupt hormone balance, and interfere with the proper development of the nervous system. Brain tissue is especially sensitive because neurons and glial cells are rapidly dividing and differentiating.
When pesticides interact with these processes, they may increase the chance of abnormal growth patterns that can later manifest as tumors.It’s important to remember that these associations don’t mean every child exposed to pesticides will develop cancer, but they do highlight an avoidable risk. For families planning pregnancy, reducing pesticide exposure as much as possible is one of the most protective steps.
A few things you can do to lower your child’s risk of cancer:
- Support maternal health before and during pregnancy with adequate thyroid function, balanced nutrition, and stress reduction. Everything the mother experiences, so does the baby.
- Limit unnecessary radiation by asking about alternatives to CT scans or X-rays, especially during pregnancy and early childhood, and requesting the lowest possible dose when imaging if necessary.
- Reduce environmental exposures by choosing cleaner household products, avoiding indoor pesticide use, and limiting plastics in food storage, especially when heating or for fatty/acidic foods.
- Promote healthy immune function by allowing safe social exposures in early childhood, prioritizing restorative sleep, and supporting fever as a natural defense rather than immediately suppressing it with medication.
- Provide nutrient-dense foods to give children the building blocks their cells need for repair and healthy growth (fresh produce, quality proteins, and minimizing processed foods high in additives or seed oils).
- Breastfeed when possible, which has been shown to lower risks of childhood leukemia and other cancers by supporting immune development and healthy gut.
- Minimize exposure to xenoestrogens, such as BPA, phthalates, and parabens, by choosing safer personal care products and avoiding microwaving food in plastic.
- Be mindful of pesticide residues in food by washing fruits and vegetables thoroughly, choosing organic when possible.
- Encourage outdoor play and sunlight exposure for healthy vitamin D levels, which support immune function and cell differentiation, both important in reducing long-term cancer risk.
The more we understand these risks, the more we can give our children the best possible chance at a healthy life. Small changes like choosing safer products, supporting maternal health, avoiding unnecessary scans, etc, can add up. When we improve our own health, we help those who come after us.