The diagnosis of bone tumors begins, as in all medical problems, with a complete medical history and a thorough physical examination. X rays >f will be taken of any bones that seem to be causing pain. Since many bone * cancers spread to the lungs, even in very early stages, the X rays are often » followed by tests to determine whether there is any evidence of lung involvement. These may include conventional chest X rays as well as cross-sectional X rays (pulmonary tomograms) and the newer computed , tomography (CT scans), and occasionally fluoroscopy, the use of a special , fluorescent screen to view internal organs via X rays.
To determine the extent of local bone destruction, CT scans also will be taken of the bone , or bones harboring the tumor. In addition, the entire skeleton may be , studied by radionuclide scans to detect any early spread to other bones. While all of these tests provide important information, the single most ^important diagnostic examination is the bone biopsy, in which a small portion of the bone is removed and then studied under the microscope.
The purpose of the biopsy is to firmly establish the diagnosis of cancer and to determine exactly what kind of cancer is present.
The biopsy may be open, meaning that a surgical incision will be made to obtain the bone i sample, or it may be made by inserting a hollow needle into the bone to ‘-_ withdraw a small amount of tissue. If an open biopsy is performed, special » care should be taken in the placement of the incision and to make it as « small as possible so as not to interfere with future surgery or radiation therapy. A misplaced, overly large biopsy may result in poor healing and spread of the cancer. If it appears that surgery will be included in the subsequent treatment, it is advisable to have the surgeon who will perform this operation also do the biopsy to ensure that it will not jeopardize the success of the subsequent surgery. In any instance, no attempt should be made to remove the entire tumor during the biopsy, as is sometimes the case in dealing with other types of cancer, nor should there be any attempt to obtain unnecessary bone samples, for fear of spreading the tumor cells.
If Ewing’s sarcoma or any other cancer involving the bone marrow is suspected, bone marrow aspiration will be performed. This is done under local anesthesia and is not painful, although there may be some discomfort when the anesthesia is injected. A small, hollow needle is used to remove bone marrow cells (Figure 14), which are then examined under a microscope to see whether the blood-forming cells are normal or abnormal or have been replaced by cancerous cells.
As our knowledge of cancer increases, the biochemical and blood tests that are performed during the diagnostic process are becoming even more important. These tests usually include a battery of liver function studies, a complete blood count, measurements of serum sodium and potassium, and kidney function tests. Still other tests, such as an evaluation of serum protein, may be performed in patients with suspected multiple myeloma or other cancers that weaken the bones and produce abnormal images of bones in X-ray studies.