- The Bones
- Are All Bone Tumors Cancerous?
- The Types of Bone Cancer
- Bone Cancer: Who's at Risk
- Recognizing Symptoms
- Treatment for Bone Cancer
Mature bones are made up of three types of tissue: compact
tissue (the hard outer portion of most bones); cancellous
tissue (spongy tissue inside the bones that contains bone
marrow, which makes blood cells); and subchondral tissue (smooth
bone tissue of the joints). A layer of cartilage covers subchondral
tissue to cushion the movement of joints.
Bones support and protect internal organs, act as levers and
braces for muscles to produce movement, and produce and store
blood cells in the bone marrow.
Are All Bone Tumors Cancerous?
Bone tumors may be benign (noncancerous) or malignant (cancerous).
Benign bone tumors are more common than malignant ones. Both
types may grow and compress healthy bone tissue and absorb
or replace it with abnormal tissue. However, benign tumors
do not spread and are rarely life-threatening.
Cancer that arises in the bone (primary bone cancer) is not
the same disease as cancer that spreads to the bone from another
part of the body (secondary bone cancer). Primary bone cancer
is rare, with approximately 2,500 new cases diagnosed each
year in the United States. More commonly, bones are the site
of tumors that result from the spread (metastasis) of cancer
from another organ, such as the breasts, lungs, and prostate.
The Types of Bone Cancer
The most common type of bone cancer is osteosarcoma, which
develops in new tissue in growing bones. Another type of cancer,
chondrosarcoma, arises in cartilage. Evidence suggests that
Ewing's sarcoma, another form of bone cancer, begins in immature
nerve tissue in bone marrow. Osteosarcoma and Ewing's sarcoma
tend to occur more frequently in children and adolescents,
while chondrosarcoma occurs more often in adults.
Bone Cancer: Who's at Risk
Although scientists are not certain what causes bone cancer,
a number of factors may put a person at increased risk. These
cancers occur more frequently in children and young adults,
particularly those who have had radiation or chemotherapy
treatments for other conditions. Adults with Paget's disease,
a noncancerous condition characterized by abnormal development
of new bone cells, may be at increased risk for osteosarcoma.
A small number of bone cancers are due to heredity. For example,
children with hereditary retinoblastoma (an uncommon cancer
of the eye) are at a higher risk of developing osteosarcoma.
Pain is the most common symptom of bone cancer. However,
symptoms may vary depending on the location and size of the
cancer. Tumors that occur in or near joints may cause swelling
or tenderness in the affected area. Bone cancer can also interfere
with normal movements and can weaken the bones, occasionally
leading to a fracture. Other symptoms may include fatigue,
fever, weight loss, and anemia. None of these symptoms is
a sure sign of cancer. They may also be caused by other, less
serious conditions. It is important to check with a doctor.
To diagnose bone cancer, the doctor asks about the patient's
personal and family medical history and does a complete medical
exam. The doctor may suggest a blood test to determine the
level of an enzyme called alkaline phosphatase. A large amount
of alkaline phosphatase can be found in the blood when the
cells that form bone tissue are very active, such as when
children are growing, when a broken bone is mending, or when
disease or a tumor causes production of abnormal bone tissue.
Because high levels of this enzyme can normally be found in
growing children and adolescents, this test is not a completely
reliable indicator of bone cancer.
X-rays can show the location, size, and shape of a bone tumor.
If x-rays suggest that a tumor may be cancer, the doctor may
recommend special imaging tests such as a bone scan, a CT
(or CAT) scan, an MRI, or an angiogram. However, a biopsy
to remove of a sample of tissue from the bone tumor is needed
to determine whether cancer is present.
The surgeon may perform a needle biopsy or an incisional biopsy.
During a needle biopsy, the surgeon makes a small hole in
the bone and removes a sample of tissue from the tumor with
a needle-like instrument. In an incisional biopsy, the surgeon
cuts into the tumor and removes a sample of tissue. Biopsies
are best done by orthopedic oncologists, who are doctors experienced
in the diagnosis of bone cancer. A pathologist, a doctor who
identifies disease by studying cells and tissues under a microscope
examines the tissue to determine whether it is cancerous.
Treatment for Bone Cancer
Treatment options depend on the type, size, location, and
stage of the cancer, as well as the person's age and general
health. Surgery is often the primary treatment. Although amputation
of a limb is sometimes necessary, pre- or post-operative chemotherapy
has made limb-sparing surgery possible in many cases. When
appropriate, surgeons avoid amputation by removing only the
cancerous section of the bone and replacing it with an artificial
device called a prosthesis.
Chemotherapy and radiation may also be used alone or in combination.
Because of the tendency for Ewing's sarcoma to metastasize
rapidly, multidrug chemotherapy is often used, in addition
to radiation therapy or surgery on the primary tumor.