Types of Cancer : Bone Cancer

Definition

Cancer that originates in the bone — primary bone cancer — is rare. Fewer than 2,500 Americans are diagnosed with this type of cancer each year. The condition affects more children than adults.

The most common forms of primary bone cancer are:

• Osteosarcoma, which occurs primarily in growing bone tissue
• Chondrosarcoma, which occurs in cartilage
• Ewing's sarcoma, which arises primarily in immature tissue in bone marrow

Osteosarcoma and Ewing's sarcoma occur most often in children, adolescents and young adults, ages 10 to 20. Chondrosarcoma is more common in adults over 50.

Treatment of bone cancer depends on the type of bone cancer, as well as its location, size and stage.

Symptoms

Pain is the most common bone cancer symptom. Although bone cancer can arise in any of your bones, it most frequently occurs in the long bones of your arms and legs.

Other possible symptoms and signs of bone cancer include:

• Weakened bones, sometimes leading to fractures
• Joint swelling and tenderness (for tumors in or near joints)
• Fatigue
• Fever
• Unintended weight loss
• Anemia

Causes

Primary bone cancer is different from secondary or metastatic bone cancer. In secondary or metastatic bone cancer, the cancer originates in a different place but spreads (metastasizes) to the bones. For example, someone with prostate cancer may develop bone lesions from the prostate cancer. But, even though the cancer has spread to the bone, it's still prostate cancer.

Metastatic bone cancer is much more common than is primary bone cancer. Additionally, primary bone cancer doesn't refer to cancer that begins in the bone marrow — the soft inner core of your bones that makes your blood cells. Bone marrow cancers include diseases such as multiple myeloma and acute and chronic leukemias.

In general, no one knows for certain what causes most primary bone cancers. Adults with Paget's disease of bone, which involves abnormal development of new bone cells, may be at increased risk of osteosarcoma.

In a few cases, bone cancers may have a hereditary component, such as in:

• Li-Fraumeni syndrome. This condition is characterized by an increased risk of many different cancers, including osteosarcoma, breast cancer, brain cancer and others.
• Rothmund-Thomson syndrome. This condition causes short stature, skeletal problems and rashes, and increases risk of bone cancer.
• Hereditary retinoblastoma. Children with this rare cancer of the eye have an increased risk of osteosarcoma.
• Multiple exostoses. Children with this inherited condition that causes cartilage bumps to form on your bones have an increased risk of chondrosarcoma.

The association with radiation
Radiation is occasionally associated with bone cancer. Exposure to radiation from a diagnostic X-ray won't harm you. But heavy doses of radiation, such as radiation therapy given for other cancers, can increase your risk of developing bone cancer, especially if you receive the therapy at a young age.

Still, radiation therapy is becoming more and more sophisticated, which may lead to fewer of such side effects. For example, doctors today are better able to regulate doses of radiation and more precisely target the tumor being treated.

When to seek medical advice

Talk to your doctor if you develop signs or symptoms that may indicate bone cancer, such as unexplained bone pain. Having bone pain doesn't necessarily mean you have bone cancer. Bone pain is more likely due to injuries or arthritis. And bone tumors are often noncancerous (benign). However, the only way to determine whether a tumor is cancerous is for a doctor to examine a sample of the tissue.

Tests and diagnosis

If your doctor suspects you have bone cancer, he or she will take a medical history and perform a physical exam. In addition, the following tests help in diagnosing bone cancer:

• Imaging tests. Tests such as X-rays, computerized tomography (CT) scans, ultrasound and magnetic resonance imaging (MRI) enable your doctor to evaluate the area of concern.
• Bone scan. Your doctor may also request a bone scan, a procedure in which you're injected with a tiny amount of radioactive material, called a tracer, which can be detected by a special camera used to create images of your bones.

Examining a tissue sample
Determining whether a tumor is malignant requires removal of a sample of tissue (biopsy) from the tumor for examination. If your doctor suspects you have bone cancer, ask for a referral to a cancer center that specializes in bone cancer before the biopsy is performed. Treatment of bone cancer requires a specialized team who work together to treat bone cancer. This team includes a medical oncologist, orthopedic surgeon, radiation oncologist and physical therapist.

Techniques for removing a sample of a suspected bone cancer include:

• Needle biopsy. Your doctor uses a thin needle to remove small pieces of tissue from the tumor. There are two types of needle biopsy — fine-needle aspiration and core biopsy. A core biopsy involves using a slightly larger needle to remove a small, solid core of tissue.
• Surgical biopsy. Your doctor makes an incision through your skin and removes either the entire tumor (excisional biopsy) or a portion of the tumor (incisional biopsy). In some cases you may need only local anesthesia. For a larger or deep-seated tumor, you'll likely require general anesthesia for the procedure. It's important that a doctor experienced in the treatment of sarcomas perform the excisional biopsy.

Grading and staging
Besides determining whether the tissue is cancerous, examining tissue can determine how aggressive the cancer is (its grade). Further testing, such as scans and blood tests, will determine if the cancer has spread and how far (its stage).

Childhood bone cancers, such as osteosarcoma or Ewing's sarcoma, are generally grouped into two stages, depending on whether the cancer is contained in one part of the body (localized) or has spread to other parts (metastasized).

Survival is based on a number of factors, including the type of cancer, at what stage the cancer was discovered and where the tumor is located. If the tumor is very small and localized, the prognosis is generally more promising than if the cancer has begun to spread.

Treatments and drugs

As with other cancers, bone cancer treatment depends on the size, type, location and stage of the cancer, including whether it has spread to the lungs or other parts of your body, and your overall health.

Surgery
Surgery is the most common treatment for bone cancer. Surgery for cancer that hasn't spread involves removing the cancer and a rim of healthy bone surrounding it.

In the past, amputation was common for bone cancer in an arm or leg. Today, advances in surgical techniques and chemotherapy before surgery (neoadjuvant chemotherapy) or after surgery (adjuvant chemotherapy) and radiation therapy make limb-sparing surgery possible in many cases. With osteosarcoma, limb-sparing surgery involves replacing the cancerous bone with an artificial device (prosthesis) or bone from another part of your body or from another person (transplant).

A well-coordinated team of doctors — including surgeons, medical oncologists, radiation oncologists, and physical medicine and rehabilitation specialists who are familiar with treatment of sarcomas — is important for increasing the chance you'll be able to have limb-sparing treatment. Specialized centers for treatment of sarcoma exist in many areas.

If osteosarcoma spreads, treatment may involve surgical removal of both the bone tumor and the metastasized cancer.

Ewing's sarcoma has a tendency to metastasize rapidly. Treatment may involve chemotherapy with multiple drugs as well as radiation therapy and surgery to remove the primary tumor.

Radiation therapy
Radiation therapy — also called radiotherapy or X-ray therapy — involves treating cancer with beams of high-energy particles, or waves (radiation), such as gamma rays or X-rays. Although radiation can affect healthy cells as well as cancer cells, it's much more harmful to cancer cells. In addition, normal cells can recover from the effects of radiation more easily than cancer cells can.

Many people with cancer undergo some type of radiation therapy. Your doctor may suggest using radiation therapy at different times during your cancer treatment and for different reasons, such as before surgery to shrink a cancerous tumor or after surgery to stop the growth of any remaining cancer cells. Radiation may also be used at the same time as chemotherapy. In addition, doctors sometimes use radiation therapy to shrink tumors to decrease the pressure, pain or other symptoms they may cause.

Chemotherapy
Chemotherapy uses medications to kill rapidly dividing cells. These cells include cancer cells, which continuously divide to form more cells, and healthy cells that divide quickly, such as those in your bone marrow, gastrointestinal tract, reproductive system and hair follicles. Healthy cells usually recover shortly after chemotherapy is complete — so, for example, your hair soon starts growing again.

Unlike radiation therapy, which treats only the part of your body exposed to the radiation, chemotherapy treats the body as a whole (systemically). Its purpose is to treat cells that may have escaped from where the cancer originated.

Depending on the type of cancer you have and whether it has spread, your doctor may use chemotherapy to:

• Shrink the cancer prior to an operation, making the operation easier
• Eliminate all cancer cells in your body, even when cancer is widespread
• Prolong your life by controlling cancer growth and spread
• Relieve symptoms and enhance your quality of life

In some cases, chemotherapy may be the only treatment you need. More often, doctors use it in conjunction with other treatments, such as surgery or radiation, to improve results.