A BRIEF INTRO TO CHILDHOOD CANCER

Cancer begins when normal cells change and grow uncontrollably. In most types of cancer, these cells form a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous).Benign tumors are usually slow-growing and do not spread to other parts of the body (metastasize). Malignant cancers can grow rapidly and spread to other parts of the body. In leukemia, a cancer of the blood that starts in the bone marrow, these abnormal cells very rarely form a solid tumor, but instead crowd out other types of cells in the bone marrow. This prevents the production of normal red blood cells, otherotherwhite blood cells, and platelets (the part of the blood needed for clotting).

Cancer in children can occur anywhere in the body, including the blood and lymph node system, brain and central nervous system (CNS), and kidneys. Most of the time, there is no known cause for childhood cancers. Childhood cancers may behave very differently from adult cancers.

Is it dangerous?

Risk factors are different for children and for adults and vary for specific types of cancer. For most childhood cancers, risk factors remain unclear.

Leukemias

As with most cancers, the cause of most types of leukemia is unknown.

Acute Lymphocytic Leukemia (ALL)

Known risk factors include:

• Sex: Overall, males are more likely to develop ALL than females.
• Age: Most new cases happen in children between the ages of 2 and 5 years.
• Race: White children are almost two times more likely to develop ALL than black children.
• Socioeconomic status (SES): Children with a higher SES have an increased risk for ALL.
• Ionizing radiation.
• Genetic conditions: Children with the following genetic conditions are at increased risk:
  • Down syndrome,
    • Children with Down syndrome are 20 times more likely to develop ALL.
  • neurofibromatosis,
  • Shwachman syndrome,
  • Bloom syndrome,
  • ataxia telangiectasia,
  • Langerhans cell histiocytosis, and
  • Klinefelter syndrome.

Acute Myelogenous Leukemia (AML)

Risk factors for AML are different than those for ALL. Known risk factors include:

• Race: Hispanic children are at highest risk.
• Chemotherapy: Children who are exposed to alkylating agents or epipodophyllotoxins during chemotherapy treatment are at increased risk.
• Ionizing radiation.
• Genetic conditions: Children with the following genetic conditions are at increased risk:
  • Down syndrome,
  • neurofibromatosis,
  • Shwachman syndrome,
  • Bloom syndrome,
  • Familial monosomy 7,
  • Kostmann granulocytopenia, and
  • Fanconi anemia.

A number of other factors have been investigated to determine their relationship with ALL and AML but any evidence has been inconsistent and limited. These factors include exposures to specific chemicals, paternal occupation, paternal smoking, maternal alcohol use, and factors related to birth. International variation in the occurrence of childhood leukemias as well as studies finding increases in risk with population growth due to in- migration in areas have lead to the theory that an infectious agent may play a role; however, studies have not been able to confirm the presence of an infectious agent.

Brain and Other Nervous System Cancers

Very little is known about the causes of brain and other nervous system cancers. Known risk factors include:

• Sex: Overall, males are more likely to develop brain and other nervous system cancers than females.
• Race: White children are more likely to develop brain and other nervous system cancers than black children.
• Radiation therapy
• Rare hereditary conditions: Children with the following genetic conditions are at increased risk:
  • Li-Fraumeni syndrome,
  • Neurofibromatosis,
  • Tuberous sclerosis
  • Nevoid basal cell syndrome,
  • Turcot syndrome.

A number of environmental factors have been investigated, but more research is needed to determine how the environment relates to brain and other nervous system cancers in children. There is some evidence that having a parent who is a farm worker or living on a farm may be associated with these cancers.

Prevention/ Cure?

Cancer prevention measures are difficult to develop for children because very little is known about what causes childhood cancers. Rare genetic conditions seem to be factors for cancers developing in children. Ask your doctor or your child's pediatrician for specific health recommendations.