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It is important that there is little delay in the diagnosis
of osteosarcoma. The earlier the diagnosis, the greater is the chance
for cure.
Signs and Symptoms of
Osteosarcoma
Pain in the affected bone is the most common complaint of
patients with osteosarcoma. At first, the pain is not constant and may
be worse at night. The pain increases with activity and may result in a
limp if a leg is involved. Swelling in the area of the pain site may
not occur until weeks later.
Depending on the location of the tumor, it may be possible to
feel a lump or mass. Although osteosarcoma may weaken the bone it
develops in, the bones do not often break. Telangiectatic
osteosarcomas, which are rare, tend to weaken bones more than other
forms of osteosarcoma. About 30% of telangiectatic osteosarcomas cause
a fracture at the tumor site. Patients with a fracture next to or
through an osteosarcoma will describe a limb that was sore for a few
months and suddenly became severely painful when the fracture occurred.
Unfortunately, limb pain and/or swelling are seen very
commonly seen in normal, active teenagers, so they are often
not thoroughly evaluated. This can delay a diagnosis. These symptoms
are less common in adults and should be a sign to see a doctor.
Imaging Studies
Bone x-ray: Doctors will usually recognize
(or at least suspect) osteosarcoma on regular x-rays of the bone.
However, a biopsy (sample of the tumor for examination under the
microscope) is needed to prove that cancer is really present.
Computed tomography (CT): The CT scan is
an x-ray procedure that produces detailed cross-sectional images of the
body. Instead of taking one picture, like a conventional x-ray, a CT
scanner takes many pictures as it rotates around you. A computer
combines these pictures into an image of a slice of your body. The
machine will create multiple images of the part of your body that is
being studied.
Often after the first set of pictures is taken, you or your
child will receive an intravenous (IV) injection of a "dye" or contrast
agent that helps better outline structures in the body. A second set of
pictures is then taken.
You or your child will need an IV line through which the
contrast dye is injected. Some people are allergic to the dye and get
hives or a flushed feeling or, rarely, have more serious reactions like
trouble breathing and low blood pressure. Be sure to tell the doctor if
you or your child has ever had a reaction to any contrast material used
for x-rays.
A CT scan of the affected bone can show if the tumor has
grown into nearby muscle, fat, etc. The scan will also help the surgeon
pick the best area to biopsy. A chest CT scan is very important in
determining if osteosarcoma has metastasized (spread) to the lungs.
Magnetic resonance imaging (MRI): MRI
scans use radio waves and strong magnets instead of x-rays. Energy from
the radio waves is absorbed by tissues of the body. The energy is then
released in a pattern affected by the type of tissue and by certain
diseases. A computer is used to translate the pattern of radio waves
given off by tissues into a very detailed cross-sectional image of
parts of the body. Not only does this produce cross sectional slices of
the body like a CT scanner, it can also produce slices that are
parallel with the length of your body. A contrast material might be
injected just as with CT scans.
MRI gives more details of the soft tissues, the bone tumor,
and the bone marrow cavity than a CT scan. It is thought to be better
for evaluating osteosarcoma. Sometimes, the MRI can help find small
tumors several inches away from the main tumor (called "skip metastases"). Finding these small
tumors is important for planning the type of surgery that is best for
each patient. MRI scans are also very helpful in looking at the brain
and spinal cord.
MRI scans are a little more uncomfortable than CT scans.
First, they take longer – often up to an hour. Also, you have to be
placed inside tube-like equipment, which is confining and can upset
people with claustrophobia (fear of enclosed places).
Chest x-ray: This test can spot cancers if
they are large enough (one-half inchor larger) that have
spread from the original site in the bone. (A CT scan of the chest is
more sensitive; it can spot very small tumors.)
Radionuclide bone scan: During a bone scan, a radioactive
tracer is injected into a vein. The most commonly used tracer is
Technetium 99. Another tracer that can also be used is Thallium 201;
this tracer seems to provide better information regarding the response
of the tumor to chemotherapy, but it also exposes children to much
higher radiation, so it is seldom used in younger people. The tumor
absorbs these radioactive materials, which are detected by a special
type of camera. A computer reconstructs images showing all the bones of
the body. Osteosarcoma will usually appear as a darker spot in the scan
indicating more concentrated radioactivity. The bone scan can also
detect spread of the osteosarcoma to the lungs and/or to other bones.
Positron emission tomography (PET): This
is a new type of radioactive scan. With PET, you or your child will
receive an infusion of glucose (a form of sugar) that contains a
radioactive atom. A special camera can detect the radioactivity. Cancer
cells in the body absorb high amounts of the radioactive sugar, because
of their high rate of metabolism. PET may be useful for looking at
spread of cancer.
Blood Tests
High levels of certain chemicals in the blood can suggest
that the osteosarcoma is more advanced than it appears. The most
important of these are called alkaline phosphatase and LDH. They are
released into the blood by osteosarcoma cells. Higher levels indicate a
worse outlook for cure.
Biopsy
A biopsy procedure takes a sample of tumor tissue to examine
under the microscope and use for certain other laboratory tests.
Probably in no other cancer is it as important to perform this
procedure properly. If the biopsy is not done properly, the affected
limb may have to be amputated (removed by cutting).
A biopsy may be done under local or general anesthesia. With
local anesthesia, the anesthetic is injected with a small needle to
numb the tissue over the sample site. During general anesthesia, drugs
are injected into a vein or are breathed in so the patient is asleep
during the operation.
There are 2 different types of biopsies: the needle biopsy
and the open biopsy.
The needle biopsies can use thin (also called fine) or thick
needles. The fine needle biopsy removes very small fragments of tissue.
With the thick needle biopsy, the surgeon obtains a cylindrical core of
tissue. Most experts recommend this thicker core biopsy.
In the open biopsy, the surgeon cuts through the skin, exposes the tumor,
and then cuts out a piece of tissue. This biopsy must be done by an expert in
bone tumors, or it’s possible the chance for saving a limb may be lost. If
possible, the opening through the skin used in the biopsy procedure should
be lengthwise along the arm or leg because this is the orientation of the
incision that will be used for the operation to remove the cancer. The entire
scar of the original biopsy will also have to be removed so planning the
biopsy incisions in this way minimizes the amount of tissue that needs to
be removed later on.
Tissue removed by biopsy is always examined under the
microscope. Examining a bone tumor may also involve tests of the
chromosomes or genes. These tests may help distinguish osteosarcoma
from other cancers that look similar under the microscope, and can
sometimes help predict whether the osteosarcoma is likely to respond to
therapy.
Revised: 03/19/2007
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