What is cancer?
Cancer, defined very simply, is when cells that grow haphazardly become abnormal shapes and sizes and then damage the surrounding cells and tissues necessary for the body to function correctly. These cancerous cells can then metastasize or move to other organs and tissues and cause damage to these tissues as well.

Common childhood cancers include:

Leukemia: Leukemia is a cancer of the blood cells. Children with lymphocytic leukemia produce many abnormal white cells that crowd the bloodstream and prevent the function of normal white cells. White cell's primary function is to protect the body from disease. There are two forms of leukemia typically seen in children: acute lymphomic leukemia (ALL) or acute nonlymphomic leukemia (ANLL) that affects other blood cells.

Lymphoma: Lymphomas are cancers that originate in the lymphatic tissues (tonsils, lymph nodes, spleen, bone marrow) and the lymphatic channels that connect them. There are two main types of lymphoma: hodgkin's disease and non-hodgkins lymphoma. In hodkin's disease there are specific malignant cells referred to as teed-sternberg cells in the lymph nodes or other lymphatic tissue. Non-hodgkin's lymphoma involves a malignant growth of lymphocytes, a type of white blood cell that collects in the lymph nodes.

Osteosarcoma: Osteosarcoma is most common in adolescents as they enter their growth spurt. It involves bone cells called osteoblasts which are responsible for bone growth. It is found most frequently in bones surrounding the knee as well as in the longer bones of the body.

Wilm's tumor: Wilm's tumor is a cancer that affects one or both kidneys. It is found most commonly in children between the ages of two and five years old. Most wilm's tumors are not discovered until they are larger in size but are usually caught before they metastasize.

Brain and spinal cord tumors: Brain and spinal cord tumors are the second most common cancers found in children. Most tumors involve the cerebellum or brain stem. Tumors can be primary (originating in brain tissue) or metastatic (tumors that originate in other tissue and spread to the brain). Primary tumors are the most common in children.

Rhabdomyosarcoma: Rhabdomyosarcoma is the most common soft tissue cancer found in children. The tumor originates in cells similar to those that normally develop into skeletal muscles of the body.

All information listed above is courtesy of the American Cancer Society website. For more information or more detailed descriptions, visit the American Cancer Society website at www.cancer.org.