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Sometimes, bone metastases are found before they have a chance
to cause any symptoms. When you are first diagnosed with cancer, your
doctor may order lab tests and imaging tests (such as bone x-rays or
bone scans) to see how far the cancer has spread. These tests may
reveal bone metastases. Or signs of bone metastasis may be found during
a routine checkup after treatment is finished.
Signs and symptoms of bone metastases
The symptoms of bone metastasis can be mild at first. You may
notice a poorer appetite and have trouble sleeping because you are
uncomfortable. These symptoms can make it hard to carry out your daily
routines.
Bone pain
Bone pain is often the first symptom of cancer that has spread
to the bone. The pain often comes and goes at first. It tends to be
worse at night and may be relieved by movement. Later on, it becomes
constant and may be worse during activity. It is important to tell your
doctor about bone pain right away. The bone might be so weakened that
it will break. This can often be prevented if the bone metastasis is
found early. Your doctor will want to x-ray the painful area and may do
scans or other imaging tests. Other diseases, such as bone infections,
arthritis, or just being very active, can also make bones hurt.
Fractures
Bones weakened from metastatic cancer may break (fracture).
The fracture can happen with a fall or injury, but a weak bone can also
break during everyday activities. These fractures often cause sudden,
severe pain. The pain may keep you from moving much at all. In some
cases, a fracture is the first sign of bone metastasis. The most common
sites of fractures are the long bones of the arms and legs and in the
bones of the spine. Sudden pain in the middle of the back, for example,
is a common sign of a cancerous bone breaking and collapsing.
Spinal cord compression
Cancer in the bones of the spine can press on the spinal cord.
The spinal cord contains nerves that allow you to move and feel what
happens to your body. Pressure on the spinal cord doesn't just cause
pain, it also can damage the nerves in the spinal cord. This can lead
to numbness and weakness, and may even cause paralysis. Most often this
affects the legs, but if tumor is pressing on the spinal cord in the
neck, the arms and the legs are affected. Sometimes the first symptom
you may have of spinal cord pressure is trouble urinating because
nerves from the spinal cord control the bladder. (See the section,
"When cancer threatens to paralyze, it's an emergency" under "Local
treatments.")
Hypercalcemia
When cancer spreads to the bones, calcium can be released into
the bloodstream. This can lead to high blood calcium levels
(hypercalcemia), which can cause problems such as constipation, nausea,
loss of appetite, and extreme thirst. The high calcium causes you to
make more urine, leading to dehydration. It can also make you feel very
tired and weak. You may be sleepy or even confused. If not treated,
hypercalcemia can even cause you to lapse into a coma.
Tell your doctor right away if you have
symptoms
It's very important for you to tell your doctors and nurses
about any new bone symptoms or changes in old symptoms. Finding and
treating bone metastasis early can help prevent problems later on.
Imaging tests to find bone metastases
X-rays
Regular x-rays of the bones may show signs of the cancer's
spread..
There are 2 types of bone metastases. In the first type, the
cancer cells dissolve some of the minerals in the bone, making an area
of the bone less dense. These are called osteolytic or lytic
metastases. They appear on x-rays as a darker hole in the gray-white
bone image. X-rays do not show bone metastases unless the cancer has
destroyed about half of the bone’s substance. Bones with
osteolytic metastases tend to break very easily.
The other type of bone metastases causes an area of the bone
to appear denser or sclerotic. These are called osteoblastic or blastic metastases.
These make an area of the bone appear denser (an area of sclerosis). On
x-rays, these metastases show up as spots that are whiter than the bone
around them. This type is common in certain cancers, such as prostate
cancer and some breast cancers. Often, bone metastases have both lytic
and blastic features.
X-rays can also find fractures (breaks) in bones that have
been weakened by metastases.
Radionuclide bone scan
This procedure helps show if a cancer has metastasized to
bones. A radioactive substance, or marker, called technetium diphosphonate
is injected into a vein. The amount of radioactivity used is low and
does not cause side effects.
This marker is attracted to diseased bone cells throughout the
entire skeleton. A scanner that detects radioactivity is used to take a
picture of the body. Areas of diseased bone will be seen on the bone
scan image as dense gray to black areas, called "hot spots." Hot spots
are often caused by metastatic cancer, although they can also be caused
by other bone problems, such as arthritis or infection. The pattern of
these diseases on a bone scan is usually different from the pattern
caused by cancer, but the doctor may need the results of other tests to
know for sure.
Bone scans can usually find metastases much earlier than
regular x-rays. Not only are bone scans useful in spotting bone
metastases, they can also track how the metastases respond to
treatments.
Sometimes bone scans fail to find cancer that has spread to
the bones. This happens most often if the metastases are purely
osteolytic (where bone is less dense). In some patients, the scan may
show no radioactivity in areas of bone that the cancer has already
destroyed.
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
the usual x-ray, a CT scanner takes many pictures as it rotates around
you. A computer then combines these pictures into an image of a slice
of your body. The machine will take pictures of many slices of the part
of your body that is being studied. If bone scans or x-rays do not show
metastases, this test can help tell if the cancer has spread into your
bones. It may be used when bone metastases are only osteolytic, since
these metastases sometimes don't show up in bone scans. Often, after
the first set of pictures is taken you will receive an injection of a
"dye" or contrast agent, to help better outline structures in your
body. A second set of pictures is then taken.
The contrast dye will be injected through an IV (intravenous;
in your vein) line. A few people are allergic to the dye and get hives,
a flushed feeling, or rarely, more serious reactions like trouble
breathing and low blood pressure. Be sure to tell the doctor if you
have ever reacted to any contrast material used for x-rays, or if you
notice a problem during the scan.
CT scans take longer than regular x-rays and you need to lie
still on a table for about 15 to 30 minutes while the scans are being
done. CT scanning is getting faster and your stay might be fairly
short. But you might feel a bit confined by the equipment you have to
lie in while the pictures are being taken.
CT scans can also be used to biopsy a suspected metastasis
precisely. For this procedure, called a CT-guided needle biopsy, you
stay on the CT scanning table while a radiologist guides the biopsy
needle toward the suspicious area. CT scans are repeated until the
doctors are confident that the needle has reached the right place. A
fine needle biopsy sample (tiny fragment of tissue) or a core needle
biopsy sample (a thin cylinder of tissue about ½ inch long
and less than 1/8 inch in diameter) is removed and looked at under a
microscope.
Magnetic resonance imaging
Magnetic resonance imaging (MRI) scans use radio waves and
strong magnets instead of x-rays. The energy from the radio waves is
absorbed and then released in a pattern formed by the type of tissue
and by certain diseases. A computer translates the pattern of radio
waves given off by the tissues into a very detailed image of parts of
the body. Like a CT scanner, MRI produces cross-sectional slices of the
body, but it can also produce lengthwise images, that go in a head to
toe direction. A contrast material might also be used in MRI scans, but
less often than with CT scans.
Because an MRI scan is very useful for looking at the spine
and spinal cord, it is the standard test used if spinal cord
compression is suspected. MRIs are also good at finding problems in
bones and joints. MRI scans are a little more uncomfortable than CT
scans. First, they take longer -- often up to an hour. Also, you are
placed inside a tunnel-like structure, which is somewhat confining. If
you have problems with tight places (claustrophobia), tell your doctor
before any MRI. The machine makes a mild thumping noise that bothers
some people. Testing centers may provide headphones with music to block
out this sound. In general, most people do well during the procedure.
Positron emission tomography
For a positron emission tomography (PET) scan, radioactive
glucose (sugar) is injected into a vein. Because cancers use glucose
(sugar) at a higher rate than normal tissues, the radioactivity tends
to concentrate in the cancer. A scanner is used to spot the radioactive
deposits. This test can find groups of cancer cells that are too small
to see on other imaging studies. .PET scanning can be helpful in
spotting areas of cancer spread. PET scans look at the whole body at
once, so they are sometimes used when your doctor thinks the cancer has
spread, but doesn’t know where. If an area on the scan looks
like it could be cancer, other tests, such as MRI or CT scan may need
to be done to check it out further. Some machines combine a CT scan
with a PET scan to better pinpoint the tumor.
Blood tests to find bone metastasis
Serum tumor markers
Some types of cancer release certain substances, called tumor
markers, into the bloodstream. Patients with these types of cancer may
have blood tests at regular intervals to see if levels of these markers
are rising. An increase in tumor marker levels can mean that the cancer
has spread, but it doesn't show where the cancer is. Other tests will
be needed to show if the metastases are in the bone or if they are
somewhere else in the body.
Prostate-specific antigen (PSA) is an example of a tumor
marker. PSA levels are higher in a man with prostate cancer, but they
should become very low after treatment. If they start to rise again, it
suggests that the cancer may have come back. If the levels are very
high, it may mean the cancer has spread to the bones. More information
about tumor markers can be found in our document: Tumor Markers.
Other blood tests
When cancer spreads to certain organs, it may damage the cells
of the organ or change the way they work. This may produce certain
substances that can be found by routine blood tests. For example:
- Calcium level:
bone metastases can dissolve the bones, leading to a high blood calcium
level.
- Alkaline
phosphatase: when the bones are broken down, the levels
of alkaline phosphatase
may also increase.
Newer types of blood tests are being studied that may be able
to detect bone metastases earlier (See the section, "What's
new in bone metastasis research and treatment?")
Urine tests
Several substances can be produced and released into the urine
when bone is damaged. One such substance that can be measured is called
N-telopeptide.
Tissue and cell sampling tests used to find
bone metastasis
If you have had cancer in the past, your doctor may be able to
tell if you have metastatic cancer based on how the bone scans or other
x-rays look. If any of your blood tests also suggest metastatic cancer,
this makes the diagnosis even more certain. When this is the case, your
doctor may not need to get a tissue sample. But if the diagnosis is not
clear, your doctor will need to take a sample from the abnormal area to
find out if it is cancer. This is called a biopsy.
Needle biopsy
There are 2 main types of needle biopsies: fine needle and
core needle.
Fine needle
biopsy or aspiration: With fine needle aspiration (FNA),
a very thin needle is used to take a small amount of fluid and small
tissue fragments from the tumor. The doctor can aim the needle at a
suspicious tumor or area that can be felt near the surface of the body.
This type of biopsy of the bone is done only if the bone is weakened or
if the cancer has spread into the soft tissue around the bone. The
biopsy is done after numbing the area. It may be uncomfortable, but is
not very painful.
There are times that the suspicious area cannot be felt or
seen because it is deep inside the body. Or the suspected metastasis
may be seen on an x-ray but there is no lump that can be felt on the
surface of the bone. In these cases, the needle can be guided by
watching it during a CT scan.
Core needle
biopsy: This type of biopsy is similar to a FNA except the
core needle biopsy uses a larger needle. The needles used for a core
biopsy remove a small cylinder of tissue (about 1/16 inch in diameter
and 1/2 inch long).
Surgical bone biopsy
Sometimes, needle biopsies don't provide an answer and a
surgical biopsy is needed. In this procedure, the surgeon cuts into the
bone to remove a small part of the tumor. This is also called an incisional biopsy.
It is rarely needed to diagnose bone metastases.
Last Medical Review: 01/13/2008 Last Revised: 05/13/2009
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