Cancers are a group of diseases that occur due to abnormal cell growth. Cancers that occur in children may vary significantly from adult cancers. Leukemia and various types of brain tumors are the two most common cancers found in children.

Most childhood cancers are diagnosed through a physical examination and a series of detailed tests. Physicians may use blood tests, x-rays, CAT scans or tissue biopsies to aid in the diagnosis of the cancer.

According to the American Cancer Society (ACS), most children are treated at a specialized children’s cancer hospital using a cancer care team. The team may include specialists such as pediatricians, oncologists, surgeons, radiation oncologists and pathologists.

The treatment for children’s cancers, as in adults, depends on the location, type and severity of the cancer. Surgery, chemotherapy and radiation therapy, as well as other forms of treatment, can be used to treat children’s cancers. These therapies may be used alone or in various combinations for the most effective treatment.

The survival rate for children’s cancers is dependent on the type of cancer and the stage. During recent years, the survival rate for children’s cancer has improved because of more advanced treatments. Ongoing research is promising for early detection of childhood cancers as well as improved treatment methods for longer survival.

In 2007, the American Cancer Society (ACS) estimates that approximately 10,400 children under the age of 14 will be diagnosed with some form of cancer.  Because of medical advances in treatment, nearly 80 percent of these children will survive five years or more. This represents a tremendous increase since the 1960s, when childhood cancer survival rates were below 50 percent.

Cancers in children are significantly different than cancer in adults as to location and type as well as the response to treatment. In general, childhood cancers tend to respond better to chemotherapy drugs. This is because childhood cancers grow rapidly and most chemotherapy drugs target cells that rapidly divide. In addition, children usually can tolerate more aggressive therapy, resulting in a better response. OVerall, children have a higher survival rate from cancer than adults.

There are a number of cancers that are commonly found in children. Each cancer has a different cell type and presents with different symptoms.

Cancer develops when cells in a part of the body grow out of control. Normal cells grow, divide and die in an orderly fashion. Cancer cells, however, grow and divide but do not readily die. Instead, they outlive the normal cells and continue to divide.

Childhood cancers most often begin in the stem cells, which are basic cells capable of producing more specialized cells. A cell change or mutation is usually the cause of most childhood cancers.

Some childhood cancers are in the form of tumors, which are localized collections of cells. Not all tumors are malignant or life-threatening. Some tumors are benign, meaning they do not contain any cancer cells. However, these tumors can still cause complications, such as interfering with the normal growth of an organ.

Other childhood cancers, such as leukemia do not usually form tumors but involve the blood. Some types of cancers are more common than others in children. According to the ACS, the overall prevalence of each type of cancer is as follows:

Some childhood cancers commonly appear in very young children, such as Wilms tumor. Other cancers, including Hodgkin’s lymphoma, tend to occur during adolescence.

Childhood cancers grow at different rates and respond differently to treatment. Some cancers spread or metastasize quickly while others do so more slowly. The location, type and stage of the cancer all determine the course of treatment and prognosis for recovery.

The ACS estimates that nearly 1,550 deaths are expected to occur among children from birth to age 14 in 2007.  Of these deaths, approximately one-third will be from leukemia. Mortality rates from childhood cancers have declined by approximately 48 percent since 1975. Despite the small percentage of children diagnosed with cancer and the improved treatments, cancer is still the leading cause of non-accidental death in children younger than 14 years of age, according to the ACS.

Survival rates for childhood cancer vary considerably depending on the type of disease. The ACS calculates a five-year survival rate for cancers as a way to view the prognosis or outlook for recovery and survival. The five-year survival rate refers to the percentage of patients who live at least five years after their cancer is diagnosed. Many children live much longer than five years, and with advances in treatments, the five-year survival rate is more favorable for recently diagnosed patients.

For the most recent time period (1996-2002), the ACS survival rates for childhood cancers are as follows:

For all childhood cancers combined, the five-year survival rates have improved significantly over the past 30 years. Before the 1970s, the survival rates were less than 50 percent. Late in the 1990s, the survival rates increased to more than 70 percent. The higher survival rates are largely due to new and advanced methods for earlier detection and treatment of the disease.

There are many types of childhood cancers and they produce different conditions. Childhood cancers can occur in bones, blood or organs. Some cancers appear in the form of tumors while others occur in the blood. Childhood cancers include:

• Leukemia. Cancer of the bone marrow that results in malignant blood cells. Leukemia is the most common form of childhood cancer, accounting for 30 percent of all childhood cancers. There are two main types that occur in children:
  
• • Acute lymphoblastic leukemia (ALL). A cancer of the lymphoid cells in the bone marrow and the lymphoid organs of the body. ALL accounts for 78 percent of all childhood leukemia cases.
    
    
  • Acute myeloid leukemia (AML). A cancer of the myeloid white blood cells (non-lymphoid), which are produced in the bone marrow.
    
    
• Cancers of the central nervous system.
  
• • Brain tumors. The most common types of brain tumors found in children are called gliomas.
    
    

    

  • Spinal cord tumors. Less common than brain tumors.
    
    
• Neuroblastoma. Solid tumor that exists outside of the brain (extracranial). This tumor can appear anywhere in the body but usually occurs in the abdomen.
  
  
• Bone cancer.  Primary bone cancer is most often seen in children and adolescents.  Metastatic bone cancer (cancer that has spread to the bone) is more common than primary bone cancer in adults. The more common forms of bone cancer in children include:
  
• • Osteosarcoma. Most common type of primary bone cancer in children. These tumors often are located at the end of long bones, close to the joints, and are associated with rapid bony growth.
    
    
  • Ewing’s sarcoma.  Less common type of primary bone cancer that can occur anywhere along the bone.
    
    
• Rhabdomyosarcoma. Most common soft tissue cancer in children. This tumor starts from skeletal muscle cells.
  
  
• Wilms tumor. A cancer that can affect one or both kidneys. It is most often found in children between 2 and 3 years of age.
  
  

  

• Germ cell tumors.  These tumors can develop in several different locations but most commonly appear in the testicles, ovaries and the bottom of the spine. These tumors occur in young children and adolescents as well as adults.
  
  
• Liver cancers. An abnormal growth (tumor) in the liver. The types of liver cancer found in children are:
  
• • Hepatoblastoma. Most common in infants or very young children, between two months and two years of age.
    
    
  • Hepatocellular carcinoma. Occurs most frequently in children between the ages of 10 and 16 years.
    
    
• Lymphomas. Tumors of the lymph tissues, which are part of the immune system. The types of lymphoma are:
  
• • Hodgkin’s lymphoma. Sometimes called Hodgkin’s disease. This cancer starts in the lymphatic tissue, which includes the lymph nodes, and organs related to the immune system. In children, it is rare before the age of five and usually diagnosed in adolescents. Only 10 to 15 percent of the cases are diagnosed in children 16 years of age and younger.
    
    
  • Non-Hodgkin’s lymphoma. This cancer also starts in the lymphoid tissue and occurs one and a half times as often as Hodgkin’s lymphoma in children.
    
    

    

Childhood cancers most often begin in the stem cells, which are the basic cells capable of producing more specialized cells. If these cells undergo a change or mutation, the result is some form of cancer.

Many types of childhood cancers appear very early in life without any apparent cause.  Unlike cancers of the adults, childhood cancers are not significantly related to lifestyle risk factors, such as tobacco use but environmental exposures have not been ruled out.

Family history and genetics may play an important role in childhood cancers. Varying forms of the same cancer may appear more than once in a family. However, in these cases, it is unknown whether the cancer is caused by genetic factors or environmental elements, such as exposure to chemicals near the family’s residence or toxins in the diet. Some scientists believe cancer could result from a combination of these factors.

Other proposed associations with childhood cancers include:

• Viruses. Certain viruses, such as the Epstein–Barr virus (EBV) and the human immunodeficiency virus (HIV), have been linked to an increased risk in developing specific childhood cancers. These cancers include Hodgkin’s and non-Hodgkin’s lymphoma. Scientists believe that the virus alters the cell until it becomes a cancer cell. Some researchers are studying associations between certain infections as triggers for childhood cancers. Recent research has also shown increased rates of childhood leukemias occurring after influenza outbreaks in Great Britain.
  
  
• Environmental agents. Pesticides, fertilizers, and power lines have been investigated as potential links to childhood cancers. There has been evidence of cancer occurring among non-related children in certain neighborhoods, schools or cities. It is unknown whether prenatal or infant exposure to these agents causes childhood cancers. Some researchers believe it is merely a coincidence rather than a direct cause and effect. A cause and effect relationship of exposure to power lines has not been established.
  
  
• Cancer treatments. High-dose radiation therapy and chemotherapy have been linked to childhood cancers. Children who have been exposed to this type of treatment may have an increased risk of developing a second malignancy later in life. Scientists believe that strong anti-cancer agents may alter the cells and possibly the immune system.

There are many theories as to possible risk factors and causes for cancers in children. However, the cause for most childhood cancers is unknown.

Cancers in children are often difficult to detect. There are many other conditions in children, such as normal illnesses, that produce similar symptoms as childhood cancer. It is important that parents have regular medical checkups for their children and be aware of any unusual symptoms that persist.

Signs and symptoms vary according to the location and type of cancer. In general, symptoms may include:

• An unusual mass or swelling.  Common locations for a mass include the abdomen, legs, arms and neck. If the mass is found near the kidneys, it may indicate Wilms tumor. A lump located on the lower spine may be a germ cell tumor.
  
  
• Muscle or joint pain. May be combined with swelling or stiffness. The pain may last for weeks and it is not associated with other factors, such as an injury or normal ‘growing’ pains. The pain may be located in an unusual place for a child, such as the lower back, indicating a possible spinal cord tumor.
  
  
• Frequent headaches. May continue for days and should be evaluated if they persist. Headaches may increase in frequency and become more severe with time. In the instance of a brain tumor, the headache may be accompanied by nausea, vomiting and motor problems.
  
  
• Sudden eye or vision changes. Blurred or double vision may indicate the presence of a brain or eye tumor.
  
  
• Unexplained paleness, fatigue or loss of energy. May be related to leukemia or tumors in vital organs.
  
  
• Sudden tendency to bruise or bleed without apparent injury may indicate leukemia.
  
  
• Prolonged, unexplained fever or sore throat.
  
  
• Rapid weight loss

These symptoms may be related to a number of medical conditions not associated with cancer. Parents must use their judgment when assessing the symptoms. They should consider the following:

• How severe are the signs and symptoms?
• How long have they lasted?
• Have they gotten worse over time?

Parents should have their children examined by a physician if they are uncertain about the appearance, severity or duration of any sign or symptoms.

A thorough examination must be conducted to determine the presence of childhood cancer. First, the physician will obtain a complete medical history from the child and the parents including any family history of cancer, symptoms, risk factors and other related medical information. Following the history, the physician will conduct a complete physical examination with emphasis on the affected areas.

In addition to the medical history and physical examination, diagnostic procedures for cancer can include one or more of the following tests:

• Blood tests. Tests that may be used in the diagnosis of childhood cancers include:
  
• • Complete blood count (CBC). Measures the number, size and maturity of blood cells in a specific volume of blood. An increased number of white blood cells can indicate an infection and abnormal cells may indicate cancer.
    
    
  • Liver function tests. Evaluate the liver’s ability to make protein, remove toxins and maintain normal blood sugar. Liver blood tests can measure certain proteins and enzymes that indicate liver injury or damage.
    
    
  • Kidney function tests. Blood urea nitrogen test (BUN) and creatinine test are two tests used to evaluate kidney function. These tests measure the amount of waste products present in the blood. Elevated levels can indicate impaired kidney function.
    
    
  • Tumor marker tests. Identify substances in the blood that are associated with certain types of cancers.
    
    
  • Genetic tests.  Evaluate DNA for abnormalities that are linked to certain diseases or conditions. Examining the blood for chromosome changes or mutations may help confirm the diagnosis of leukemia.
    
    
• Biopsy.  A removal of a sample of tissue, usually from a tumor.  The tissue is examined under a microscope by a pathologist for evidence of cancer cells. A tissue biopsy is necessary for the diagnosis of cancer.
  
  
• Bone marrow biopsy. A small amount of bone marrow tissue is removed, usually from the hip bone. If only bone marrow fluid is taken, it is a bone marrow aspiration. The tissue and/or fluid is examined for normal and abnormal cells.
  
  
• Spinal tap (lumbar puncture). A small amount of cerebral spinal fluid (CSF) is removed from the spinal canal through a special needle that is placed into the lower back. CSF is evaluated for pressure, infection, or abnormal cells. It is the fluid that surrounds a child’s brain and spinal cord.
  
  
• X-rays. Test that uses radiation energy beams to produce images on film. X-rays may be taken of any part of the body to detect a growth or abnormality of an organ.
  
  
• CAT scan.  Imaging procedure that uses computer technology to produce cross sectional images of the body. The test may be done with or without dye (contrast material). CAT scans show detailed images of the selected part of the body and can help determine the size, shape and position of a tumor and enlarged lymph nodes.
  
  
• Magnetic resonance imaging (MRI). A procedure that uses powerful magnets, radio waves and a computer to create detailed images of organs and structures in the body.
  
  
• PET scan. A radioactively controlled glucose (sugar) substance is injected into the vein and the body is viewed by a scanner. Cancer cells absorb the substance and malignant areas appear as hot spots on the images.
  
  
• Ultrasound. Imaging technique that uses high frequency sound waves and a computer to create images of blood vessels, tissues and organs. This test is used to evaluate the function of internal organs and blood flow and can detect tumors in the abdomen, liver and kidneys.
  
  
• Lymphangiogram (LAG). A type of radiologic study that detects abnormalities in the lymph system. Dye is injected into the lymph system for analysis. This test is rarely used today because newer studies are more easily performed and more reliable.

The type of tests that are used to diagnose cancer in children vary depending on the suspected cancer. For example, leukemia does not produce tumors, so a tissue biopsy would not be performed to diagnose the cancer.

Most children with cancer are treated in specialized centers especially designed for pediatric cancers. According to the American Cancer Society (ACS), 94 percent of children in the United States are treated in a cancer center that is a member of the Children’s Oncology Group (COG). These centers are associated with a university and usually with a children’s hospital. In addition, these centers can offer the most up-to-date treatment through participation in clinical trials, or studies of promising new therapies. Many private practice pediatric oncologists are participating members of the COG and can direct therapy as well.

Treatment for children with cancer is primarily planned by a cancer care team. This team includes healthcare professionals who work together to provide a comprehensive treatment plan. The care team may include the following individuals:

• Pediatrician
  
  
• Oncologists (medical, radiation and surgical)
  
  
• Surgeons (including sub-specialists such as urologists and neurosurgeons)
  
  
• Pathologists
  
  
• Hematologist
  
  
• Nurses
  
  
• Therapists (respiratory, physical, occupational and speech)
  
  
• Psychologists and education professionals
  
  
• Dietitians
  

A specific treatment plan will be established by physicians based on the child’s status, including:

• Child’s age, overall health and medical history
• Type and stage of cancer
• Treatment options
• Child’s tolerance for specific medications and procedures
• Prognosis for the course of the disease
• Medical and parental opinion or preferences

Some childhood cancers will be treated similarly to the same cancer in adults and some treatments will vary. Cancer treatments may be used alone or in combination with each other. They include:

• Surgery. Depending on the type of cancer, surgical removal of all or part of the cancerous tissue may be an option.
  
  
• Chemotherapy. These powerful anti-cancer drugs are used to kill cancer cells. The drugs work by interfering with the cancer cells’ ability to reproduce. The type of drugs, the method of administration and the schedule of treatment depend on the cancer. Chemotherapy may be used in combination with radiation therapy and/or surgery. Some chemotherapy may affect normal organs either during treatment or months to years after treatment. Although there are some exceptions, most childhood cancers initially respond well to chemotherapy. Cancers in children tend to grow fast and chemotherapy is particularly effective against rapid-growing cells. 
  
  
• Radiation therapy. This treatment uses high powered x-rays to kill cancer cells. Radiation therapy is used in different ways depending on the type and location of the cancer. Administration is not painful, although it does have some side effects. In children, radiation therapy in large doses can interfere with normal growth and development. In certain cancers, such as Hodgkin’s lymphoma, the dose of radiation is lowered and combined with chemotherapy. In children, radiation may provide a cure for cancer, control the disease or help relieve its symptoms.

During treatment, psychological counseling is essential for children and their families to cope with the emotional difficulties associated with cancer and the treatment. Support groups specific to the cancer are typically available and can be beneficial throughout the treatment period.

Unlike adult cancers, childhood cancers are not associated with lifestyle risk factors, such as smoking or alcohol use. For that reason, there is no real way to prevent cancers in children. If there is a family history of cancer, parents may inform their pediatrician for monitoring of their children. However, most cancers in children do not have a strong genetic link. Survivors of childhood cancer may experience treatment-related side effects several months or years after their cancer.  They are also at greater risk to develop another cancer later in life. Numerous studies have been conducted among childhood cancer survivors. Some of these studies have shown an increased risk of organ malfunction, cognitive impairments, hearing loss (after use of certain chemotherapy drugs) and increased risks of social problems or suicidal behavior as adults. The Children’s Oncology Group has recently released long-term follow-up guidelines for managing survivors of childhood cancer.

There is a significant amount of research being conducted in childhood cancers. One of the leading research groups, Children’s Oncology Group (COG), was formed in 2001 from four major pediatric clinical trials groups in North America. The COG now consists of thousands of doctors, nurses, scientists and cancer experts who work to discover new treatments for childhood cancer.

The COG has developed a five-year scientific plan detailing planned clinical trials, laboratory studies and patient care research. This research group is working to:

• Identify the genes active in cancer cells and their role in causing cancer.
  
  
• Develop drugs called biological agents that can be used target the genes in cancer cells.
  
  
• Identify proteins made by cancer cells and not by normal cells.
  
  
• Develop antibodies that attack the proteins in cancer cells and make them inactive
  
  
• Evaluate possible risk factors including exposure to infectious agents, chemicals, radiation and environmental toxins
  
  
• Assess prenatal and early postnatal factors and their possible role in childhood cancers
  
  
• Investigate the role of family and genetic factors

Another study called The Childhood Cancer Survivor Study (CCSS) is studying various aspects of childhood cancer. Research areas include:

• Monitoring the U.S. and international trends in incidence and mortality rates for childhood cancers
  
  
• Studies to better understand the cellular process and ways to suppress cancer cell growth and survival
  
  
• Long-term effects of cancer and its therapy on childhood cancer survivors
  
  
• Education of childhood cancer survivors regarding long term effects of treatment

In addition, there are many clinical trials being conducted by research groups at cancer centers around the world. These clinical trials focus on the newest and most advanced treatments with the goal of improving survival rates for children with cancer. The cancer care team can best determine if a child is a candidate for any clinical trials.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients or their parents may wish to ask their doctor the following questions about childhood cancers:

1. What type of cancer does my child have?
   
   
2. What types of tests will my child need to undergo?
   
   
3. What are my child's treatment options?
   
   
4. What are the risks associated with these treatments?
   
   
5. Who will be involved in the treatment planning?
   
   
6. How long will my child receive treatment? Will the treatment affect my child's growth and development?
   
   
7. What is my child's prognosis for this type of cancer?
   
   
8. What are the chances the cancer will return?
   
   
9. Will my child be at a higher risk for other cancers?
   
   
10. How will my child be monitored?
    
    
11. Is there a genetic link for this type of cancer?
    
    
12. Are my other children at risk for developing cancer?