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