Cells in many parts of the body can become cancerous when they grow out of control, and they often spread (metastasize) to other areas of the body.  As cancer cells grow, they often damage important structures in the body, consume an increasing share of the body's nutrition and weaken the body's defenses against infection and other illnesses.

In contrast to adult cancers, that are the second most frequent cause of death in the U.S., and increase in frequency with advancing age, cancer is uncommon in children.  Many adult cancers are associated with exposure to carcinogens (cancer-causing) chemicals like those in tobacco or alcohol, ionizing radiation, infection with certain viruses and bacteria, and are made more likely by lifestyle risk factors such as obesity, lack of physical activity, and unhealthy nutrition. 

Some adult cancers and most childhood cancers come from random mutations (changes) in the genes of reproducing cells. Because the changes happen randomly and unpredictably, there is no effective way to prevent them.  And a small number of children, as well as adults, have a genetic propensity to getting cancer

After accidents, cancer is the second leading cause of death in children ages 1 to 14.  About 15,000 children in the U.S. under the age of 19 are diagnosed with cancer each year and more than 1000 will die.¹

If there is any good news about cancer in children it is that in the last 40 years, the overall 5 year survival rate for children’s cancer has increased from 10% to nearly 85%. There are approximately 375,000 adult survivors of children’s cancer living in the United States.  Survival rates vary depending on the type of cancer, from more than 90% for Hodgkin Lymphoma, Wilm’s Tumor and acute lymphoblastic leukemia, to 64% to 77% for brain, bone and soft tissue childhood cancers.²  Unfortunately a high proportion of children who survive cancer suffer serious late effects such as secondary cancers, muscular difficulties and infertility.

The types of cancers that develop in children are often different from the types that develop in adults. The most frequently diagnosed childhood cancers that are  leukemia, lymphoma, and brain cancer. As kids enter the teen years, osteosarcoma (bone cancer) is more common. 

The most common cancers of children age 0-19 are:^{3 4}

• Leukemia: 29%
  
• Brain and Central Nervous System: 26%
• Neuroblastoma: 6%
• Non-Hodgkin Lymphoma: 5%
• Wilms Tumor: 5%
• Bone Tumors: 3%
• Hodgkin Disease: 3%
• Rhabdomyosarcoma: 3%
• Thyroid Carcinoma: 3%
• Germ Cell Tumors: 3%
• Retinoblastoma: 2%
• Melanoma: 2%
• Other: 11%

Diagnosis can be difficult because cancer symptoms are often similar to those caused by much more common illnesses or injuries.  It is important to have a child evaluated by a doctor or competent medical practitioner if they have unusual signs or symptoms that do not go away, such as:

• An unusual lump or swelling
• Unexplained paleness and loss of energy
• Easy bruising
• An ongoing pain in one area of the body
• Limping
• Unexplained fever or illness that doesn’t go away
• Frequent headaches, often with vomiting
• Sudden eye or vision changes
• Sudden unexplained weight loss

Once cancer has been diagnosed, it's important for parents to seek help from a medical center that specializes in pediatric oncology (treatment of childhood cancer).  In the United States, most children and teens with cancer are treated at a center that is a member of the Children’s Oncology Group (COG).  All of these centers are associated with a university or children’s hospital. These centers offer the advantage of providing treatment by a team of specialists with expertise in care of childhood cancers, as well as the other needs of children and teens with cancer and their families. This team usually includes pediatric oncologists (childhood cancer doctors), surgeons, radiation oncologists, pediatric oncology nurses, physician assistants (PAs), and nurse practitioners (NPs). These centers also have psychologists, social workers, child life specialists, nutritionists, rehabilitation and physical therapists, and educators who can support and educate the entire family.

With some exceptions, childhood cancers tend to respond better than adults to treatment, but children (especially very young children) are more likely to be affected by radiation therapy if it is needed.  Chemotherapy, radiation therapy, and cancer treatments such as surgery and administration of other drugs also can cause long-term side effects, so children who have had cancer will need careful follow-up for the rest of their lives.

When a child is diagnosed with cancer, it affects many family members and aspects of the family’s life. The American Cancer Society provides advice about coping with these changes in If Your Child Is Diagnosed With Cancer and general advice about childhood cancer at https://www.cancer.org/cancer/cancer-in-children.html

Links
Website with information on Cancer in Children:

Cancer in Children, American Cancer Society