Doctors use many tests to diagnose cancer and find out if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.
Imaging tests, such as an x-ray, may be used to find out whether the cancer has metastasized. Benign and cancerous tumors usually look different on imaging tests (see below). A benign tumor has round, smooth, well-defined borders. A cancerous tumor has irregular, poorly defined border because of aggressive growth. There may also be evidence of bone destruction on an image of a cancerous tumor. Imaging tests may suggest a diagnosis of bone cancer, but a biopsy will be performed whenever possible to confirm the diagnosis and find out the subtype. It is extremely important for a patient to be seen by a sarcoma  specialist before any surgery or a biopsy is performed.
Your doctor may consider these factors when choosing a diagnostic test:
- Age and medical condition
- Type of cancer suspected
- Severity of symptoms
- Previous test results
In addition to a physical examination, the following tests may be used to diagnose bone cancer:
Blood tests . Some laboratory tests may help detect bone cancer. Alkaline phosphatase and lactate dehydrogenase levels in the blood may be higher in patients with osteosarcoma or Ewing’s sarcoma. However, it is important to note that alkaline phosphatase is normally high when cells that form bone tissue are very active (for example, when children are growing or a broken bone is healing), so high levels do not always mean cancer. Abnormal glucose tolerance may be found in people with chondrosarcoma.
X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation.
Bone scan . A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancerous cells, appear dark.
Computed tomography (CT or CAT) scan . A CT scan creates a three-dimensional picture of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a vein to provide better detail.
Magnetic resonance imaging (MRI) . An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. MRI scans are used to check for any tumors in nearby soft tissue.
Positron emission tomography (PET) scan . A PET scan is a way to create picture of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body. This substance is absorbed mainly by organs and tissues that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.
Integrated PET-CT scan . This scanning method collects images from both CT and PET scans at the same time, and then combines the images. This technique helps the doctor look at both the structure and how energy is used by the tumor and normal tissue. This information can help doctors plan treatment and determine the benefits of different treatments.
Biopsy . A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). The type of biopsy (needle or incisional, see below) performed depends on where the cancer is located. However, sometimes a biopsy may not be able to be performed.
For a needle biopsy, a small hole is made in the bone, and a tissue sample is removed from the tumor with a needle-like instrument. During an incisional biopsy, the tissue sample is removed after a small cut is made in the tumor.
Learn more about what to expect when having common tests, procedures, and scans .
After these diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer; this is called staging . Learn more about the first steps to take after a diagnosis of cancer .