Bone Cancer

Illustration of Bone Cancer

Bone cancer is a malignant tumor that arises from the cells that make up the bones of the body. This is also known as primary bone cancer. Primary bone tumors are tumors that arise in the bone tissue itself, and they may be benign or malignant (bone cancer). Benign (non-cancerous) tumors in the bones are more common than bone cancers.

When cancer is detected in bones, it either originated in the bones (as in primary bone cancer) or has spread to the bone after originating elsewhere (a metastasis or secondary cancer that spread to the bones). When cancer is detected in bone, it most often is metastasis that has started in another organ or part of the body and then spread to the bones. This cancer that has metastasized to the bone is named for the site where original cancer began (for example, metastatic prostate cancer that has spread to the bone). Breast, prostate, and lung cancers are among the types of cancers that commonly spread to the bone in their advanced stages. Less commonly, cancer can begin within the bone as primary cancer of the bone, and this is true bone cancer. Primary and metastatic secondary bone cancers are often treated differently and have different prognoses.

Other cancers may begin in the bone even though they are not considered to be true bone cancers. Lymphoma is a cancer of the cells that are responsible for the immune response of the body. Lymphoma usually begins in the lymph nodes, but it sometimes begins in the bone marrow. Multiple myeloma is another cancer of the immune cells that typically begins in the bone marrow. These tumors are not considered primary bone cancers because they do not arise from the actual bone cells.

This article focuses on primary bone cancer, which is cancer of the bone cells themselves.

Pain is the most common symptom of bone cancer. The bone pain may initially develop at certain times of the day, often at night, or with physical activity. The pain tends to progress and worsen over time. Sometimes, the pain may be present for years before the affected person seeks treatment. Sometimes bone cancer is detected incidentally when X-rays or imaging studies are performed for another reason. Occasionally, a mass, swelling, or lump is felt around the area of bone cancer. Bone fractures can also occur at the site of bone cancer because the underlying bone structure has weakened. Less common symptoms are caused by compression or disruption of nerves and blood vessels in the affected area. These symptoms can include numbness, tingling, tenderness, or a decrease in blood flow beyond the site of the tumor, causing a cold hand or foot with weak or absent pulses.

There are several different types of bone cancer, and they are often treated differently. Knowing the precise type of bone cancer is essential for developing an optimal treatment plan. Some of the most common types of bone cancer are as follows.

Osteosarcoma

Osteosarcoma is the most common type of bone cancer. Osteosarcoma occurs most commonly in older children, teenagers, and young adults (10-19 years of age), and it is more common in males. The cancerous tissue in osteosarcoma in young people tends to develop at the ends of long bones in areas of active bone growth, often around the knee, either at the end of the thighbone (femur) or the shinbone (tibia) near the knee. The next most common location for bone cancer is in the bone of the arm (humerus). Nevertheless, osteosarcoma can develop in any bone. Depending on the appearance of the tumor cells under the microscope, there are also several different subtypes of osteosarcoma.

Chondrosarcoma

Chondrosarcoma is the second most common bone cancer. It arises from cartilage cells that are attached to or cover the bone. It is more common in people older than 40 years of age, and less than 5% of these cancers occur in people under 20 years of age. It may either grow rapidly and aggressively or grow slowly. Chondrosarcoma is most commonly found in the bones of the hips and pelvis.

Ewing sarcoma

Ewing sarcoma, sometimes referred to as the Ewing sarcoma family of tumors (ESFTs), is an aggressive form of bone cancer that is most common in children 4-15 years of age. It can occur either in the bones or in the soft tissues and is believed to arise from primitive nerve tissue. ESFTs are more common in males than in females. The most common location for Ewing sarcoma is the middle portion of the long bones of the arms and legs.

Pleomorphic sarcoma (malignant fibrous histiocytoma) of bone

Pleomorphic sarcoma is cancer formerly referred to as malignant fibrous histiocytoma or MFH. This term is still used frequently. Pleomorphic sarcomas are typically not cancers of bone but soft tissues. However, they may arise in the bone in up to 5% of cases. Pleomorphic sarcomas typically occur in adults and can be found anywhere in the body.

Fibrosarcoma

Fibrosarcoma is an uncommon type of bone cancer. It most commonly arises behind the knee in adults.

Chordoma

Chordoma is a very rare cancer usually seen in people over 30 years of age. It is most commonly located in either the lower or upper ends of the spinal column.

As with other cancers, there is no one cause of bone cancer. In general, cancers arise when normal cell growth and proliferation are disrupted, allowing abnormal cells (cancer cells) to divide and grow uncontrollably. Several hereditary and environmental factors are likely involved in the development of bone cancers.

About 2,300 cases of bone cancer are diagnosed in the U.S. each year. Primary bone cancers are not common and account for far less than 1% of all cancers. Bone cancers are more common in children and younger adults than in older people. Cancer found in the bones of an older adult usually has spread to the bone after originating from another location in the body.

Risk factors for bone cancers include the following:

• Previous treatment with radiation therapy
• Previous chemotherapy with drugs known as alkylating agents
• Mutation in a gene known as the retinoblastoma (Rb) gene or other genes
• Associated conditions, such as hereditary retinoblastoma, Paget's disease of bone, Li-Fraumeni syndrome, Rothmund-Thomson syndrome, tuberous sclerosis, and Diamond-Blackfan anemia
• Implantation of metal to repair previous fractures

A variety of imaging tests may be used to detect bone tumors, including bone cancers. Very early bone cancers may or may not be apparent on plain X-rays. CT scans and MRI scans are more precise in defining the location of bone cancers.

A bone scan is a test that uses radioactive material to produce images of the entire skeleton. This may allow the localization of bone cancer anywhere in the body. This test is not specific to bone cancers and can also reveal areas of inflammation as found with arthritis, fractures, and infections.

While many bone cancers have a characteristic appearance in imaging studies, a biopsy (tissue sample) must be taken to precisely determine what kind of cancer is present and confirm the diagnosis. The biopsy is a procedure to acquire a sample of a piece of the tumor that is examined under a microscope. The tissue sample may be obtained with a needle inserted through the skin into the tumor or with a surgical operation.

At present, there are no screening tests available to detect early bone cancers.

An operation to remove the cancer is the mainstay of treatment for bone cancers. Surgical techniques can remove most bone cancers without requiring amputation of the affected limb. In some cases, amputation may be avoided with limb-sparing surgery. Sometimes, muscles and other tissues that surround cancer also have to be removed. Reconstructive surgery may be needed, in addition to cancer resection, to help maximize the function of the limb.

Ewing sarcoma, osteosarcoma, and other bone cancers may require chemotherapy in addition to surgery.

Radiation therapy is the typical treatment for chondrosarcoma.

Ewing sarcomas that do not respond well to high-dose chemotherapy may require radiation therapy and even a stem-cell transplant. In this procedure, the patient's stem cells (blood cells that have the potential to develop into all the different kinds of blood cells) are harvested from the bloodstream. After high doses of chemotherapy medications to destroy the bone marrow, the harvested stem cells are next returned to the body, as with a blood transfusion. Over the next three to four weeks, the stem cells produce new blood cells from the bone marrow.

Targeted therapies are specially designed treatments that aim treatment specifically at the cancer cells. For example, denosumab is a monoclonal antibody that acts to block the activity of specialized bone cells called osteoclasts. This medication has been used in the treatment of giant cell tumors of bone that have recurred after surgery or cannot be removed by surgery. Imatinib is a targeted therapy drug that can block the signals from certain mutated genes that cause tumor cells to grow. Imatinib has been used to treat some chordomas that have spread or recurred after treatment.

Clinical trials are another type of treatment for bone cancers. In clinical trials, doctors test promising new medications, combinations of medications, or procedures. Clinical trials are carefully controlled research studies. Talk to your doctor if you think you may be interested in participating in a clinical trial.

Analgesics (pain-relieving medications) treat the pain of bone cancer. These may be nonprescription or prescription medications. Mild-to-moderate pain is treated with medications such as acetaminophen (Tylenol) or nonsteroidal anti-inflammatory medications (NSAIDs), including ibuprofen (Advil, Motrin) and naproxen (Naprelan, Aleve, Naprosyn, Anaprox). However, people taking anticancer chemotherapy drugs sometimes must avoid NSAIDs because of the increased risk of bleeding.

Prescription medications are used for moderate-to-severe cancer pain. Opioids -- stronger narcotic pain medications -- like codeine, morphine, oxycodone, hydromorphone, and fentanyl may be required to control severe pain. Sometimes a combination of medications is used to treat cancer pain. Opioid medications can be associated with side effects like drowsiness, constipation, and nausea.

The prognosis, or outlook, for survival for bone cancer patients, depends upon the particular type of cancer and the extent to which it has spread. The overall five-year survival rate for all bone cancers in adults and children is about 70%. Chondrosarcomas in adults have an overall five-year survival rate of about 80%.

The five-year survival rate specifically for localized osteosarcomas is about 60%-80%. If cancer has spread beyond bone, the survival rate is about 15%-30%. Osteosarcomas tend to have a more favorable prognosis if they are located in an arm or leg, respond well to chemotherapy and are generally completely removed at surgery. Younger patients and females also tend to have a more favorable prognosis than males or older patients.

Ewing sarcomas have a five-year survival rate of about 70% when they are found in a localized stage. If they have spread outside of the bone, the survival rate drops to 15%-30%. Factors that are associated with a more favorable prognosis for Ewing sarcomas include smaller tumor size, age less than 10 years, having cancer in an arm or leg (instead of in the pelvis or chest wall), and having a good response to chemotherapy drugs.

Since the exact cause of bone cancer is poorly understood, there are no lifestyle changes or habits that can prevent these uncommon cancers.