Medicine Winning Some Battles Against Childhood Cancer

Cancer is the leading cause of disease-related deaths in children under the age of 20. Every year, about 12,400 children and teens are diagnosed with cancer, and approximately 2,300 children die. Despite these grim statistics, it is important to note that childhood cancer is still relatively rare, affecting only about 14 of every 100,000 children on average each year, according to the National Cancer Institute. More importantly, survival rates for some childhood cancers have improved greatly over the last generation as medical research uncovers new treatment options.

Childhood cancers follow the same disease process as adult cancers. Cells grow out of control, developing abnormal sizes and shapes and destroying neighboring cells. The cells can ultimately spread (metastasize) to other organs and tissues. Cancer saps a child's strength, destroys organs and bones, and weakens the body's defense against other illnesses.

Common Childhood Cancers
According to the National Institutes of Health, the most common types of childhood cancers - which account for over one-half of the new cases - include leukemias (blood cell cancers) and brain and other central nervous system tumors.

"About one-third of childhood cancers are some form of leukemia. The most common type of leukemia in children is acute lymphocytic leukemia," according to James T. Casper, MD, Medical College of Wisconsin Professor of Pediatrics and Chief of Pediatric Hematology/Oncology Clinic at Children's Hospital of Wisconsin.

"About 20 percent of solid tumors are brain tumors - gliomas and medulloblastomas, with other solid tumors being less common. As children enter their teen years, there is also an increase in the incidence of osteosarcoma (bone cancer). The sites of cancer are different for each type," he added.

What Causes Cancer in Children?
In adults, some cancers can be traced to lifestyle choices, such as smoking, diet, or even environmental factors. Some cancers are also attributable to genetics. But in children, the factors that trigger cancer are usually not the same factors that may cause cancer in adults.

While concerned and frightened parents often believe the disease must somehow be their "fault," it is rare for childhood cancers to come from a genetic condition. In almost all cases, childhood cancers arise from non-inherited mutations in the genes of growing cells. These mutations occur randomly, so there is no way to prevent them, although researchers are working on finding some explanations.

"Why does somebody get leukemia? We don't have an answer. In my 30 years in practice, I may have seen one or two families where two siblings had cancer, but that is quite rare. Most of the time, there is no family history," Dr. Casper said.

Treatment
The symptoms of some childhood cancers may be easy to miss - swollen glands, frequent infections, or bruises. These are such common symptoms in children, it is possible that parents and doctors might suspect other childhood illnesses when cancer first appears.

Children's cancers are often treated in some of the same ways as adult cancer. The exact type of treatment a child receives depends on the type of cancer. Most children with cancer receive surgery, radiation therapy (use of x-rays to kill cancer cells), chemotherapy (use of drugs to kill cancer cells) or a combination of the three. "The disease dictates what type of treatment is used," Dr. Casper said.

Radiation is a common treatment for childhood cancers such as brain tumors and Hodgkin's disease. Radiation is a stream of high-energy particles that destroy or damage cancer cells. Before radiation therapy begins, a radiation oncologist will meet with the patient and family to explain the details of treatment, which can take several weeks to complete.

Chemotherapy is the use of strong drugs to destroy cancer cells within the body. How much chemotherapy medication is given depends on the type of cancer the child has and how well the process works in the individual child.

As they do in adults, chemotherapy drugs can cause side effects such as nausea, vomiting, hair loss, fatigue, anemia, abnormal bleeding, and increased risk of infection because of damage to the bone marrow, along with kidney damage and menstrual problems. Other side effects may include skin problems, hearing loss and liver damage.

"The drugs are administered according to a child's weight. Kids are treated very aggressively and they are often more resilient than adults," Dr. Casper said. "Much is dictated by the stage of the disease."

When children have osteosarcoma or other solid tumors that can be safely removed, surgery is often performed. After surgery, chemotherapy or radiation may also be used to destroy any remaining cancer cells.

Survival Improves
Survival rates for childhood cancer have risen sharply over the past 20 years, according to the National Institutes of Health. In the United States, more than 75 percent of children with cancer are now alive five years after diagnosis, compared with about 60 percent in the mid-1970s. Much of this dramatic improvement is due to the development of improved therapies.

"One big issue right now is finding out the long-term side effects of chemotherapy and radiation," said Dr. Casper. "A generation ago, we were just happy if we were able to cure a patient. Now that we have higher survival rates, we want to know more about how the chemotherapy drugs and radiation are going to affect these children as they grow into adulthood.

"For example, how might the drugs affect the heart or other organs? How does Drug X perform versus Drug Y? We are also looking at the psychological impact of childhood cancer. All of these things are being studied at sites around the country."

"Thirty years ago, we were treating many cancers in the same way. That is no longer true as we have a much better understanding of the biological and genetic features of pediatric cancers today. This knowledge is allowing us to be more precise in our treatment decisions," Dr. Casper said.

JoAnn Petaschnick
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.