Alex's Lemonade Stand Foundation for Childhood Cancer

The steady increase in the incidence of childhood cancer since 1975 gives rise to the question: What causes childhood cancer? But before delving into this question, it is important to clarify what incidence rates explain. In the United States, the childhood cancer incidence rate has increased over the past several decades, from approximately 13–14 per 100,000 children in the late 1970s to about 19 per 100,000 children in recent years (including 2022), representing a roughly one-third increase over time based on SEER registry data.¹⁸

However, this does not mean that the actual cases of childhood cancer increased by 40%. Incidence rates are population based, which gives scientists more information about what is happening in a population of people (in this case children in the United States) versus raw numbers. 

Understanding why the incidence rate is rising is important as scientists study cancer; however, the cause of a vast majority of childhood cancers remains unknown. Here is what is known:

1. Childhood cancer is distinctly different from adult cancer. It has unique molecular and biological characteristics. How does this relate to causation? Well, this simply means the things that can cause adult cancer don’t necessarily cause childhood cancer. 
2. Tracking and classifying cancer rates continues to improve and really did not begin in earnest until 1973¹⁹ with the launch of Surveillance, Epidemiology, and End Results (SEER) Program. Before SEER, childhood cancer data were fragmented and largely based on hospital records and mortality statistics, making long-term incidence comparisons less precise. 
3. Classification systems have grown and shifted to identify more tumors as malignancies. Specifically, previously “benign” brain tumors started to be classified as malignant in the mid-1980s. The World Health Organization also continues to classify and define more subtypes of childhood cancer. This does not mean there is more cancer; it simply means more diseases are considered cancer.²⁰
4. The causes of childhood cancer remain largely unknown. Most cases arise from random genetic mutations that occur during development or in early childhood. 
5. Current studies indicate that 10-18% of all cancers are caused by cancer predisposition, including some types of retinoblastoma (see Section 2, page 33). These can be spontaneous syndromes or inherited, like Li-Fraumeni (see Section 2, page 35), which increases a child’s lifetime risk of cancer by 90% (females) and 70% (males).²¹
6. Environmental exposures are suspected contributors to childhood cancer increases, but there are not widespread conclusive studies. Exposure to radiation could play a role in the development of secondary cancers, as could environmental toxins like pesticides. Several studies on cancer clusters—geographic areas with high childhood cancer incidence rates—point to some correlation between exposure and cancer risk.²²