(
Cáncer infantil: Osteosarcoma
)
Osteosarcoma is the most common type of bone cancer, and the
sixth most common type of cancer in children. Although other types
of cancer can eventually spread to parts of the skeleton,
osteosarcoma is one of the few that actually begin in bones and
sometimes spread (or
metastasize
) elsewhere, usually to the lungs or other bones.
Because osteosarcoma usually develops from
osteoblasts
(the cells that make growing bone), it most commonly affects teens
who are experiencing a growth spurt. Boys are more likely to have
osteosarcoma than girls, and most cases of osteosarcoma involve the
knee.
Most osteosarcomas arise from random and unpredictable errors in
the DNA of growing bone cells during times of intense bone growth.
There currently isn't an effective way to prevent this type of
cancer. But with the proper diagnosis and treatment, most kids with
osteosarcoma do recover.
Risk for Childhood Osteosarcoma
Osteosarcoma is most often seen in teenage boys, and evidence
shows that teens who are taller than average have an added risk for
developing the disease.
Kids who have inherited one of the
rare cancer syndromes
also are at higher risk for osteosarcoma. These syndromes include
retinoblastoma
(a malignant tumor that develops in the retina, usually in children
younger than age 2) and
Li-Fraumeni syndrome
(a kind of inherited genetic mutation). Because exposure to
radiation is another trigger for DNA mutations, children who have
received radiation treatments for a prior episode of cancer are
also at increased risk for osteosarcoma.
Symptoms of Osteosarcoma
The most common symptoms of osteosarcoma are pain and swelling
in a child's leg or arm. It occurs most often in the longer
bones of the body - such as above or below the knee or in the upper
arm near the shoulder. Pain may be worse during exercise or at
night, and a lump or swelling may develop in the affected area up
to several weeks after the pain starts. Pain that persistently
wakes the child up at night or pain at rest are of particular
concern. In osteosarcoma of the leg, the child may also develop an
unexplained limp. In some cases, the first sign of the disease is a
broken arm or leg, because the cancer has weakened the bone to make
it vulnerable to a break.
If your child or teen has any of the above symptoms, it's
important to see a doctor.
Diagnosing Osteosarcoma
To diagnose osteosarcoma, the doctor will likely perform a
physical exam, obtain a detailed medical history, and order X-rays
to detect any changes in bone structure. The doctor may also order
a
magnetic resolution imaging
(MRI)
scan of the affected area, which will find the best area to biopsy
and show whether the osteosarcoma has spread from the bone into
nearby muscles and fat. The doctor will also order a bone biopsy to
obtain a sample of the tumor for examination in the lab. This is
best done by an orthopedic surgeon experienced in the treatment of
osteosarcoma (orthopedic oncologist).
Sometimes the doctor does a needle biopsy, using a long hollow
needle to take a sample of the tumor. A local anesthesia is
typically used in the area that's being biopsied.
Alternatively, the doctor may order an open biopsy, in which a
portion of the tumor is removed in the operating room by a surgeon
while the child is under general anesthesia.
If a diagnosis of osteosarcoma is made, the doctor will order CT
chest scans as well as a bone scan and, sometimes, additional MRI
studies. These will show if the cancer has spread to any part of
the body beyond the original tumor. These tests will be repeated
after treatment starts to determine how well it is working and
whether the cancer is continuing to spread.
Treating Osteosarcoma
Treatment of osteosarcoma in children includes
chemotherapy
(the use of medical drugs to kill cancer cells and shrink the
cancer) followed by surgery (to remove cancerous cells or tumors)
and then more chemotherapy (to kill any remaining cancer cells and
minimize chances of the cancer coming back). Surgery often can
effectively remove bone cancer, while chemotherapy can help
eliminate remaining cancer cells in the body.
Surgical Treatment
Surgical treatments for osteosarcoma consist of either
amputation or limb-salvage surgery.
Currently, most teens with osteosarcomas involving an arm or leg
can be treated with limb-salvage surgery rather than amputation. In
limb-salvage surgery, the bone and muscle affected by the
osteosarcoma are removed, leaving a gap in the bone that is filled
by either a
bone
graft
(usually from the bone bank) or more often a special metal
prosthesis. These can be appropriately matched to the size of the
bone defect. The risk of infection and fracture is higher with bank
bone replacement and therefore metal prostheses are more commonly
used for reconstruction of the bone after removal of the tumor.
If the cancer has spread to the nerves and blood vessels
surrounding the original tumor on the bone, amputation (removing
part of a limb along with the osteosarcoma) is often the only
choice.
When osteosarcoma has spread to the lungs or elsewhere, surgery
may also be performed to remove tumors in these distant
locations.
Chemotherapy
Chemotherapy is usually given both before and after surgery. It
eliminates small pockets of cancer cells in the body, even those
too small to appear on medical scans. A child or teen with
osteosarcoma is given the chemotherapy drugs intravenously (through
a vein) or orally (by mouth). The drugs enter the bloodstream and
work to kill cancer in parts of the body where the disease has
spread, such as the lungs or other organs.
Short-Term and Long-Term Side Effects
Amputation carries its own short-term and long-term side
effects. It usually takes at least 3 to 6 months until a young
person learns to use a prosthetic (artificial) leg or arm, and this
is just the beginning of long-term psychological and social
rehabilitation.
With a limb salvage surgery, one usually starts bending the knee
or the affected body part almost immediately. A continuous passive
motion (CPM) machine, that continuously bends and straightens the
knee may be used to improve motion for tumors around the knee.
Physical therapy and rehabilitation for 6 to 12 months following
surgery usually enables the child to walk initially with a walker
or crutches and then without any assistive devices. Early
complications after surgery include infection and slow healing of
the surgical wound, and the metal prosthetic device or the bank
bone may need to be replaced in the long term. Other late problems
might include fracture of the bank bone or failure of the bank bone
to heal to the child's bone, which might require more
surgery.
Many of the medications used in chemotherapy also carry the risk
of both short-term and long-term problems. Short-term effects
include anemia, abnormal bleeding, and increased risk of infection
due to destruction of the bone marrow, as well as kidney damage and
menstrual irregularities. Some drugs carry a risk of bladder
inflammation and bleeding into the urine, hearing loss, and liver
damage. Others may cause heart and skin problems. Years after
chemotherapy for osteosarcoma, patients have an increased risk of
developing other cancers.
Chances for a Cure
Recent studies have reported that survival rates of 60% to 80%
are possible for osteosarcoma that hasn't spread beyond the
tumor, depending on the success of chemotherapy.
Osteosarcoma that has spread cannot always be treated as
successfully. Also, a child whose osteosarcoma is located in an arm
or leg generally has a better prognosis than one whose disease
involves the ribs, shoulder blades, spine, or pelvic bones.
New Treatments
Treatments are being developed and researched with new
chemotherapy drugs. Other research is focused on the role certain
growth factors might play in the development of osteosarcoma. This
research may be used to develop new medications to slow these
growth factors as a way to treat the cancer.
For osteosarcomas that cannot be removed surgically, studies are
now underway to test treatments that use new combinations of
chemotherapy and localized, high-dose radiation.
Reviewed by:
Mihir Thacker, MD
Date reviewed: January 2008
Originally reviewed by:
Donna Patton, MD
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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