Childhood cancer is a rare, yet complex, group of diseases. Medical professionals classify these cancers into major categories, which helps in understanding their origins and guiding treatment approaches.
Major Categories of Childhood Cancer
Childhood cancers are broadly grouped based on the type of cell or tissue where they initially form. This classification helps guide specialized treatment. Main categories include leukemias, which affect blood-forming tissues, and brain and spinal cord tumors, arising in the central nervous system.
Other categories include lymphomas, originating in the lymphatic system, and neuroblastoma, a cancer developing from immature nerve cells. Additionally, there are Wilms tumor (kidney cancer), bone cancers (like osteosarcoma and Ewing sarcoma), retinoblastoma (affecting the eye), rhabdomyosarcoma (a soft tissue sarcoma), and germ cell tumors (arising from reproductive cells).
Common Types Within Each Category
Within the major categories, specific types of cancer are frequently observed. For leukemias, Acute Lymphoblastic Leukemia (ALL) accounts for about 75% of cases, developing from early forms of white blood cells called lymphocytes. Acute Myeloid Leukemia (AML) makes up most of the remaining cases, originating from myeloid cells that form other blood cells.
Brain and spinal cord tumors include forms such as astrocytomas, the most frequent type of glioma, which develop from glial cells. Medulloblastoma is another common malignant brain tumor, typically forming in the cerebellum. Ependymomas, arising from cells lining the fluid-filled spaces of the brain and spinal cord, are also seen, often in children under five.
Lymphomas are divided into Hodgkin lymphoma and non-Hodgkin lymphoma. Hodgkin lymphoma is characterized by Reed-Sternberg cells. Non-Hodgkin lymphoma includes types like aggressive mature B-cell non-Hodgkin lymphoma, lymphoblastic lymphoma, and anaplastic large cell lymphoma. Burkitt lymphoma, a fast-growing B-cell lymphoma, frequently appears as large tumors in the abdomen.
How Childhood Cancers Differ from Adult Cancers
Childhood cancers differ from adult cancers in their origins, locations, and treatment responses. The causes of most childhood cancers are often unknown, with some linked to inherited genetic mutations or those occurring during early development. In contrast, many adult cancers are associated with lifestyle choices, environmental exposures, and the cumulative effects of aging.
Childhood cancers frequently arise in tissues like blood, bone, and the brain. Adult cancers, however, more commonly originate in epithelial tissues, such as those found in the breast, lung, colon, or prostate. Pediatric cancers often grow more aggressively and may be more advanced at diagnosis.
Despite their aggressive nature, children often respond better to chemotherapy and can tolerate higher doses over shorter periods. This improved response is partly because children generally have healthier organs and fewer co-existing health issues. However, treatments in children can lead to different or more pronounced long-term side effects due to their developing bodies.
Prevalence of Childhood Cancer Types
While many types of childhood cancer exist, some are diagnosed more frequently than others. Leukemias are the most common overall, accounting for approximately 30% of all pediatric cancers. Acute Lymphoblastic Leukemia (ALL) is the most prevalent type of leukemia in children.
Brain and spinal cord tumors constitute the second most common group, representing about 20% of all cases in patients under 15 years old. Following these are lymphomas, which make up about 15% of childhood cancers.