Pediatric Cancer Bone

Childhood bone cancer accounts for about six percent of all childhood cancers. Bone cancer in children can be either primary or secondary:

  • Primary bone cancer originates in the bone.
  • Secondary bone cancer is due to metastasis (spreading) of a cancer occurring in another part of the body.

Because our bones are such a rich source of nutrients, secondary bone cancer can occur from the metastasis of virtually all other cancers. Secondary cases of bone cancer are much more common than primary bone cancers.

Bone Cancer Incidence

The two most common primary bone cancers in children are osteosarcoma and Ewing’s sarcoma. Each year approximately 700 children are diagnosed with primary bone cancer.

Bone cancer that occurs in children under five years of age is very rare. The incidence of bone cancer in children slowly increases until it peaks at age 13 for girls and 15 for boys, corresponding with the typical growth spurt that occurs at this time. Childhood bone cancer is more common in boys than girls.

Causes of Bone Cancer

Only a few known causes and risk factors of bone cancer in children exist:

  • ethnicity (Ewing’s sarcoma almost exclusively affects white children)
  • existing genetic conditions (retinoblastoma, Li-Fraumeni syndrome, Rothmund-Thomson syndrome)
  • exposure to high doses of radium
  • prior radiation therapy or chemotherapy.

While these conditions may contribute to the development of bone cancer, they do not account for all occurrences, so the exact cause of bone cancer in children is not known in all cases.

In addition, a number of potential risk factors have been suggested as causes of bone cancer. These include:

  • fetal exposure to X-rays
  • lower than average birth length
  • maternal exposure to certain fertilizers, herbicides or pesticides
  • prior injury at the site of the tumor
  • taller than average height or stature.

Information about the causes of bone cancers is limited. Researchers are currently collecting more data that will hopefully clarify the risk factors and causes for bone cancer in children.

Bone Cancer Locations

Bone cancer most commonly affects the growing ends (the metaphyses) of the long bones of the leg and arm, especially at the knee and shoulder.

While osteosarcoma most often occurs in the long bones of the leg, Ewing’s sarcoma is often found in these locations:

  • bones of the pelvis
  • clavicle
  • ribs
  • sternum
  • vertebrae.

Bone Cancer Symptoms

In most cases of childhood bone cancer, the child will complain of painful legs, especially at night or when active. When the cancer occurs near a joint, such as a knee, symptoms can also include swelling and tenderness.

General symptoms that may also occur include:

  • anemia
  • decreased appetite
  • fatigue
  • fever
  • weight loss.

As the disease progresses, some kids also develop a limp. Occasionally, the bone structure may be so affected that fractures occur.

Diagnosing Bone Cancer

The initial visit to the doctor is typically prompted by the child’s persistent symptoms. The doctor will perform a physical examination and order the following:

  • blood tests
  • CT scan or MRI
  • X-rays.

If the laboratory and imaging results are suggestive of bone cancer, a biopsy will be taken to confirm the diagnosis.

Bone Cancer Treatment

Once a diagnosis is made, a CT scan of the chest and a radionuclide bone scan can help detect any possible metastasis, or spreading, of the cancer to other parts of the body, such as the lungs. Repeated scans throughout treatment help the doctor evaluate the effectiveness of the treatments and monitor the cancer for metastasis. Three aspects central to bone cancer treatment include:

  • chemotherapy
  • radiation
  • surgery.

Chemotherapy

Bone cancer patients often receive chemotherapy both before and after surgery. As a systemic treatment, chemotherapy helps eliminate any rogue cancer cells that would promote metastasis. Regular blood tests during post-surgical chemotherapy (adjuvant chemotherapy) help the doctor monitor the effectiveness of the treatment and organ function.

While chemotherapy is vital to bone cancer treatment, it can produce a number of negative side effects. Side effects can include:

  • hair loss
  • loss of appetite
  • low blood cell count
  • low sperm count
  • mouth sores
  • vomiting/nausea.

Not all of these side effects will occur in all patients, and a doctor will be able to determine which side effects a particular patient is more likely to experience.

Radiation

Used to shrink tumors, external beam radiation therapy may be used prior to surgery to treat Ewing’s sarcoma tumors. It may be used following surgery for osteosarcoma when removal of the entire tumor is not possible. Radiation can also be used to control pain and inflammation.

Surgery

The primary element of bone cancer treatment is surgical removal of the tumor. If the tumor has affected a joint and limb-sparing surgery is possible, a sophisticated endoprosthetic (an artificial body part placed inside the body) designed to grow with the child may be implanted. Bone tissue from the pelvis may be grafted, or connected, to the remaining healthy bone tissue to replace the removed bone.

Full rehabilitation may take a year or more. Physical therapy is demanding on the post-surgical patient. Patients who are lax or do not participate in physical therapy may lose the use of the affected limb.

When the tumor is large or has affected surrounding tissues, nerves and blood vessels, amputation is the only option. The amputated limb will be fitted with an external prosthetic limb (artificial limb). With appropriate physical therapy, most patients can walk on their own three to six months after amputation surgery.

Bone Cancer Prognosis

The five-year survival rate (the percentage of patients who have lived at least five years after treatment) is relatively high for bone cancer that is localized, or limited to one area of the body. Nearly 70 percent of patients with localized bone cancer survive.

Cancers that have metastasized at the time of diagnosis have a lower five-year survival rate, which varies according to where and how far the cancer has spread.

Recovering from Bone Cancer

Removal of the tumor is only one aspect of bone cancer treatment. Because bone cancer is often diagnosed during the sensitive teenage years, its psychological effects can be profoundly devastating.

A support structure that goes beyond the cancer center is vital to survival. Friends and family that can encourage continued participation in physical therapy, healthy food choices, completion of schoolwork and re-entry into life are a necessary component of bone cancer rehabilitation for children and teenagers.

Resources

American Cancer Society (2005). Bone cancer. Retrieved September 4, 2007, from the ACS Web site: http://documents.cancer.org/102.00/102.00.pdf.

American Cancer Society (2006). Complementary and Alternative Methods for Cancer Management. Retrieved September 4, 2007, from the ACS Web site: http://www.cancer.org/docroot/ETO/content/ETO_5_1_Introduction.asp.

Gurney, J.G., Swensen, A.R.