Tests for Osteosarcoma

Osteosarcomas are usually found because a person is having signs or symptoms, which prompt a visit to a doctor. If a bone tumor is suspected, exams and tests will be needed to find out for sure.

If an osteosarcoma is found, other tests will then be done to learn more about it.

Medical history and physical exam

If a person has signs or symptoms that suggest they might have a tumor in or around a bone, the doctor will take a complete medical history to find out more about the symptoms.

A physical exam can often provide information about a possible tumor. For example, the doctor may be able to see or feel an abnormal lump or mass.

The doctor may also look for problems in other parts of the body. When people (especially adults) have cancer in the bones, it’s often the result of cancer that started somewhere else and then spread to the bones.

If the doctor suspects a person could have osteosarcoma (or another type of bone tumor), more tests will be done. These might include imaging tests, biopsies, and/or lab tests.

Imaging tests

Imaging tests use x-rays, magnetic fields, or radioactive substances to create pictures of the inside of the body. Imaging tests might be done for a number of reasons, including:

• To help find out if a suspicious area might be cancer
• To help determine if a cancer might have started in another part of the body
• To learn how far cancer has spread
• To help determine if treatment is working
• To look for signs that the cancer might have come back

People who have or might have osteosarcoma will have one or more of these tests.

Bone x-ray

This is often the first test done if a bone tumor is suspected. Doctors can often recognize a bone tumor such as an osteosarcoma based on plain x-rays of the bone. But other imaging tests might be needed as well.

Even if results of an x-ray strongly suggest a person has osteosarcoma, a biopsy (described below) will still be needed to confirm that it is cancer rather than some other problem, such as an infection.

Magnetic resonance imaging (MRI) scan

MRIs create detailed images of soft tissues in the body using radio waves and strong magnets instead of x-rays, so no radiation is involved. A contrast material called gadolinium is often injected into a vein before the scan to better see details.

An MRI is often done to get a more detailed look at a bone mass seen on an x-ray. MRIs can usually show if the mass is likely to be a tumor, an infection, or some type of bone damage from another cause.

MRIs can also help determine the exact extent of a tumor, as they can show the marrow inside bones and the soft tissues around the tumor, including nearby blood vessels and nerves. MRIs can also show small bone tumors several inches away from the main tumor (called skip metastases). Knowing the extent of an osteosarcoma is very important when planning surgery.

An MRI scan usually shows better details than a CT scan (described below).

Computed tomography (CT) scan

A CT scan combines many x-ray pictures to make detailed cross-sectional images of parts of the body. If a bone x-ray shows a tumor, CT scans are sometimes used to see if the tumor has grown into nearby muscle, fat, or tendons, although MRI is often better for this.

A CT scan of the chest is often done to look for spread of the cancer to the lungs. CT scans may also be done to look for the spread of the cancer to other parts of the body.

Chest x-ray

This test is sometimes done to see if an osteosarcoma has spread to the lungs. It can find larger tumors, but it is not as good as a CT scan for spotting smaller tumors. If a CT scan of the chest is done, a chest x-ray probably won’t be needed.

Bone scan

A bone scan can help show if a cancer has spread to other bones, and is often part of the workup for people with osteosarcoma. This test is useful because it can show the entire skeleton at once. (A positron emission tomography [PET] scan, described below, can often provide similar information, so a bone scan might not be needed if a PET scan is done.)

For this test, a small amount of low-level radioactive material is injected into the blood and travels to the bones. A special camera that can detect the radioactivity then creates a picture of the skeleton.

Areas of active bone changes attract the radioactivity and appear as “hot spots” on the skeleton. Hot spots may suggest areas of cancer, but other bone diseases can also cause the same pattern. To make an accurate diagnosis, other tests such as plain x-rays, MRI scans, or even a bone biopsy might be needed.

Positron emission tomography (PET) scan

For a PET scan, a form of radioactive sugar (known as FDG) is injected into the blood. Because cancer cells in the body are growing quickly, they absorb large amounts of the sugar. A special camera can then create a picture of areas of radioactivity in the body. The picture is not detailed like a CT or MRI scan, but it provides useful information about the whole body.

PET scans can help show the spread of osteosarcomas to the lungs, other bones, or other parts of the body. They can also be used to see how well the cancer is responding to treatment.

Many machines can do a PET and CT scan at the same time (PET/CT scan). This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed appearance of that area on the CT scan.

To learn more about this and other imaging tests, see Imaging (Radiology) Tests.

Biopsy

The results of imaging tests might strongly suggest that a person has osteosarcoma (or some other type of bone cancer), but a biopsy (removing some of the tumor for viewing under a microscope and other lab testing) is the only way to be certain.

If the tumor is in a bone, it is very important that the biopsy is done by doctors experienced in treating bone tumors. Whenever possible, the biopsy and surgical treatment should be planned together, and the same doctors should do both. Proper planning of the biopsy can help prevent later complications and might reduce the amount of surgery needed later on.

Two main types of biopsies can be used for bone tumors.

Core needle biopsy

For these biopsies, the doctor uses a hollow needle to remove a small cylinder of tissue from the tumor. The biopsy is usually done with local anesthesia, where numbing medicine is injected into the skin and other tissues over the biopsy site. In some cases, sedation or general anesthesia (where the patient is asleep) may be needed.

Often, the doctor can aim the needle by feeling the suspicious area if it's near the surface of the body. If the tumor can’t be felt because it's too deep, the doctor can guide the needle into the tumor using an imaging test such as a CT scan. This CT-guided needle biopsy is typically done by a doctor who is an interventional radiologist.

Surgical (open) biopsy

In an open biopsy, a doctor (typically an orthopedic surgeon) cuts through the skin, exposes the tumor, and then cuts out a piece of it. These biopsies are usually done in an operating room with the patient under general anesthesia (in a deep sleep). They can also be done using a nerve block, which numbs a large area of the body.

Again, it's important that the biopsy is done by an expert in bone tumors, or it could result in problems later on. For example, if the tumor is on the arm or leg and the biopsy isn't done properly, it might lower the chances of saving the limb. If possible, the incision for the biopsy should be lengthwise along the arm or leg because this is the way the incision will be made during the operation to remove the cancer. The entire scar of the original biopsy will also have to be removed, so making the biopsy incision this way lessens the amount of tissue that needs to be removed later on.

Lab tests

Testing the biopsy samples

All samples removed by biopsy are sent to a pathologist (a doctor specializing in lab tests) to be looked at with a microscope. Tests looking for chromosome or gene changes in the tumor cells might also be done. These tests can help tell osteosarcoma from other cancers that look like it under the microscope, and they can sometimes help predict whether the osteosarcoma is likely to respond to treatment.

If osteosarcoma is diagnosed, the pathologist will assign it a grade, which is a measure of how quickly the cancer is likely to grow and spread, based on how the tumor cells look. Cancers that look somewhat like normal bone tissue are described as low grade (and tend to grow more slowly), while those that look very abnormal are called high grade. For more on grading, see Osteosarcoma Stages.

Blood tests

Blood tests are not needed to diagnose osteosarcoma, but they may be helpful once a diagnosis is made. For example, high levels of chemicals in the blood such as alkaline phosphatase and lactate dehydrogenase (LDH) can suggest that the osteosarcoma may be more advanced.

Other tests such as blood cell counts and blood chemistry tests are done before surgery and other treatments to get a sense of a person’s overall health. These tests are also used to monitor a person’s health while they are getting chemotherapy.

Finding out that you or a loved one has cancer can be overwhelming. Coping with Cancer discusses the emotions and concerns you might face and things you can do to help work through them.