If bone cancer is suspected, the first step in diagnosis is a discussion with the doctor about the patient’s personal and family medical history. The doctor will then perform a complete medical examination and conduct various tests.
One key test is an examination of a patient’s blood for alkaline phosphatase, an enzyme that can be found at particularly high levels in the blood when bone-forming cells are very active. This kind of high activity occurs normally when a young child’s bones are growing, or when a broken bone is mending. Otherwise, it might be an indication that a tumor is creating abnormal bone tissue. Since alkaline phosphatase may rise in response to other causes, high levels do not necessarily indicate that a patient has bone cancer, but they do signal the need for further evaluation.
A physician will usually order imaging tests such as an x-rays, which will allow the doctor to see any unusual bone growths. This may be followed by a bone scan, to see if there are other abnormal areas in the skeleton. Before a bone scan, a small amount of a slightly radioactive substance known as a “tracer” is injected into a vein. After a few hours, the tracer material will collect in places where there is new bone growth. A computed tomography (CT) or magnetic resonance imaging (MRI) scan is often ordered to show the exact size, shape, and extent of the suspected bone tumor, and to determine if it has invaded surrounding tissue.
A positron emission tomography (PET) scan may also be used in bone cancer diagnosis. Unlike other imaging techniques that focus on a precise area of the body, PET scans have the ability to show cancer growth throughout the whole body. PET and CT scans can be used in combination to pinpoint the exact location of cancer. Often, CT scans of the chest are used to see if the tumor has spread to the patient’s lungs.
Finally, a biopsy of the suspicious bone tissue is needed to make a definite diagnosis. If the tumor is small enough, the doctor may remove the entire tumor, which is called an excisional biopsy. In other cases, the doctor may make a small opening in the skin and remove just a small part of the tumor for analysis — a procedure known as an open biopsy. Or the doctor may do a needle biopsy, in which a sample of the tumor is removed through the skin using a needle.
It is very important that the biopsy be performed by an experienced and skilled surgeon, because an improperly performed biopsy may limit treatment options later.
A pathologist examines the biopsy samples to determine whether or not the tissue is cancerous, and if it is, to identify the exact type of cancer. Determining the exact type of cancer is critical, because not all types of bone cancer respond to the same kinds of treatment.