The first symptom of bone metastasis is almost always pain. If you have cancer and begin to experience pain in a bone, you should report it to your doctor right away. Sometimes, if the cancer isn't promptly treated, the bone may break. Your doctor will want to x-ray the painful area and do scans or other imaging tests. Other diseases, such as bone infections, arthritis, or just being very active, can also make bones hurt.

When a cancer is first diagnosed, doctors will recommend a series of other tests to find out how far it has spread. Depending on certain features of the primary tumor (such as its size and exact type), your doctors will estimate your risk of metastasis and may recommend tests to search for it. If no metastases are found, then the primary cancer will be treated and you will see the doctor at regular intervals for follow-up care. One of the main purposes of follow-up care is to find out if the cancer is beginning to come back either at the original site or elsewhere at a metastatic site.

Symptoms of Bone Metastasis

The symptoms of bone metastasis can be mild at first. You may notice your appetite decreasing and have trouble sleeping because you are uncomfortable. These symptoms can make it hard to perform your usual activities.

Bone Pain

Bone pain is usually the first symptom of metastasis 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. The bone might be so weakened that it will break. This can often be prevented if the bone metastasis is found early.

Fractures

Broken bones (fractures) can occur and cause severe pain. They 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 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 backbone can press on the spinal cord. The spinal cord contains nerves that allow you to move and feel what happens to your body. This is why pressure on the spinal cord is one of the most serious complications of bone metastasis. Not only can the pressure on the spinal cord cause pain, it can damage your spinal cord so that your legs become numb and even paralyzed. Sometimes the first symptom you may have of spinal cord pressure is trouble urinating because nerves from the spinal cord control the bladder.

Hypercalcemia

If the cancer has metastasized to many bones, you may develop hypercalcemia (high blood calcium levels caused by release of calcium from bones). This can cause nausea, loss of appetite, thirst, and extreme tiredness. If left untreated, hypercalcemia can even cause you to lapse into a coma.

For these reasons, it's very important for you to tell your doctors and nurses about any new bone symptoms or changes in old symptoms. Early detection and early treatment of bone metastasis can help reduce your chances of further problems later on.

Sometimes bone metastases are found before they have a chance to cause any symptoms. Signs of bone metastases may be found through lab and imaging tests (such as bone x-rays or bone scans) that are done when the doctor is learning the stage of your cancer (called staging), or in a routine checkup after treatment is finished.

Imaging Tests to Detect Bone Metastasis

X-rays

During staging or follow-up of a cancer, your doctor may get x-rays of your bones. These may show evidence of the cancer's spread to one or more bones. X-rays will not show bone metastases unless the cancer has destroyed about half of the bone’s substance.

Bone metastases can change the appearance of bone in 2 ways. One way is when metastases dissolve some of the minerals in the bone, which makes the bone less dense. These are called osteolytic or lytic metastases, and appear on x-rays as a dark hole in the gray-white bone image. Bones with osteolytic metastases tend to break very easily.

Other cancers, especially prostate cancers and some breast cancers, cause osteoblastic or blastic metastases. These make the bone appear denser (sclerosis). On x-rays, these metastases appear as spots that are whiter than the surrounding bone. This is the second way metastases can change the way bones look.

X-rays can also find fractures (breaks) in bones that are weakened by metastases.

Radionuclide Bone Scan

A radionuclide bone scan helps show whether a cancer has metastasized to bones. You will be given an injection of a radioactive substance called technetium diphosphonate. The injection itself is the only uncomfortable part of the entire scanning procedure. The amount of radioactivity used is low compared with the much higher doses used in radiation therapy, and this low level of radiation does not cause any side effects.

The radioactive substance is attracted to diseased bone cells throughout the entire skeleton. Areas of diseased bone will be seen on the bone scan image as dense gray to black areas called hot spots. These areas may suggest metastatic cancer, although arthritis, infection, or other bone diseases can also cause hot spots. The pattern of these diseases is usually different from the pattern caused by cancer. To tell the difference between these conditions, the cancer care team may use other imaging tests or take bone biopsies. Bone scans can find metastases much earlier than regular x-rays. Not only are bone scans useful in spotting bone metastases, they can also track how metastases respond to treatments.

Sometimes bone scans fail to find areas of cancer spread to the bones. This happens most often if the metastases are osteolytic. In some patients, the scan may show no radioactivity in certain areas of bone that have already been destroyed by the cancer.

Computed Tomography

The computed tomography (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. This test can help tell whether your cancer has spread into your bones. It is especially important when the 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 intravenous injection of a "dye" or radiocontrast agent that helps better outline structures in your body. A second set of pictures is then taken.

CT scans can also be used to precisely guide a biopsy needle into a suspected metastasis. For this procedure, called a CT-guided needle biopsy, you stay on the CT scanning table, while a radiologist advances a biopsy needle toward the suspicious area. CT scans are repeated until the doctors are confident that the needle is within the mass. 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 examined under a microscope.

CT scans take longer than regular x-rays, and you need to lie still on a table for 15 to 30 minutes while the scans are being done. But just like other computerized procedures, CT scanning is getting faster and your stay might be fairly short. However, you might feel a bit confined by the equipment you have to lie in while the pictures are being taken.

The contrast dye will be injected through an IV (intravenous) 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.

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 images that are parallel with the length of the body. A contrast material might also be used in MRI scans, but less often than with CT scans.

MRI scans are particularly useful for looking at the spine and spinal cord. If your doctor thinks your cancer is pressing on your spinal cord, this is the best test to find out. 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. The machine also makes a mild thumping noise that bothers some people. Some testing centers will provide headphones with music to block out this sound. In general, most people tolerate the procedure well.

Positron Emission Tomography

Positron emission tomography (PET) is usually performed with glucose (a form of sugar) that contains a radioactive atom. A small amount of the radioactive material in injected into a vein. Cancer cells in the body absorb large amounts of this radioactive sugar. A special camera is used to detect the radioactivity. PET scanning is useful to see whether the cancer has spread to lymph nodes. PET scans are also useful when your doctor thinks the cancer has spread, but doesn’t know where. PET scans can be used instead of several different x-rays because they scan your whole body. Newer devices combine a CT scan with a PET scan to better pinpoint the tumor.

Blood Tests to Detect 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. For example, high prostate-specific antigen (PSA) levels in a man who has already had surgery or radiation therapy for prostate cancer suggest the cancer may have come back or, especially if the levels are very high, may have spread to the bones. A high blood calcium level is another sign that the cancer may have spread to the bones.

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, bone metastases often cause high levels of alkaline phosphatase. Although this substance is made by both the liver and bones, there are special chemical tests that can tell if it comes from bone.

Urine Tests

Several substances are produced when bone is damaged. These are often secreted into the urine. 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 can usually diagnose metastatic cancer based on how the bone scan or other x-rays look. If any of your blood tests also suggest metastatic cancer, this makes the diagnosis even more certain. Because of this, biopsies are usually not needed. But if the diagnosis is not clear, your doctor will need a biopsy sample from the abnormal area to find out if it is cancer.

Needle Biopsy

There are 2 types of needle biopsies: fine needle and core needle.

Fine Needle Biopsy or Aspiration

With fine needle aspiration (FNA), a very thin needle and a syringe are 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 with a local anesthetic. 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

One approach your doctor might take is to do a standard bone marrow biopsy. In this procedure, the doctor puts a needle through the back of your pelvic bone after it has been numbed with local anesthetic. This can be moderately uncomfortable. A core of bone and marrow will be removed. Often, this test will show cancer even though cancer has not been seen on x-rays of the pelvis. The benefit of this approach is that it is simpler than trying to biopsy the suspicious sites because they may be hard to get at or particularly painful to biopsy. But if there is a real question about a particular area of bone then it can be biopsied with a needle.

Usually, the doctor who performs a bone marrow biopsy uses x-rays or CT scans for guidance. 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, called an incisional biopsy, the surgeon cuts into the bone to remove a small part of the tumor. This procedure is not done very often.