Bone Cancer Diagnosis
- X-ray of bone
- Bone biopsy
- Bone scan showing size and location of tumor
- Alkaline phosphatase may be elevated
Physical examination and routine x rays may yield enough evidence to diagnose benign
bone tumors, but removal of tumor tissue for microscopic analysis (biopsy) is the only
sure way to rule out malignancy.
Bone Cancer Diagnosis - needle biopsy
A needle biopsy involves using a fine, thin needle to remove small bits of tumor, or a
thick needle to extract tissue samples from the innermost part (the core) of the growth.
An excisional biopsy is the surgical removal of a small, accessible tumor. An iNational Cancer institutesional
biopsy is performed on tumors too large or inaccessible to be completely removed. The
surgeon performing an iNational Cancer institutesional biopsy cuts into the patient's skin and removes a portion
of the exposed tumor. Performed under local or general anesthetic, biopsy reveals whether
a tumor is benign or malignant and identifies the type of cancer cells the malignant tumor
contains.
Bone cancer is usually diagnosed about three months after symptoms first appear, and
20% of malignant tumors have metastasized to the lungs or other parts of the body by that
time.
Imaging techniques for Bone Cancer Diagnosis
The following procedures are used, in conjunction with biopsy, to diagnose bone cancer:
- Bone x rays. These x rays usually provide a clear image of osteosarcomas.
- Computerized axial tomography (CAT
scan) is a specialized x ray that uses a rotating beam to obtain detailed information
about an abnormality and its physical relationship to other parts of the body. A CAT scan
can differentiate between osteosarcomas and other types of bone tumors, illustrate how
tumor cells have infiltrated other tissues, and help surgeons decide which portion of a
growth would be best to biopsy. Because more than four of every five malignant bone tumors
metastasize to the lungs, a CAT scan of the chest is performed to see if these organs have
been affected. Chest and abdominal CAT scans are used to determine whether Ewing's sarcoma
has spread to the lungs, liver, or lymph nodes.
- Magnetic resonance imaging (MRI) is
a specialized scan that relies on radio waves and powerful magnets to reflect energy
patterns created by tissue abnormalities and specific diseases. An MRI provides more
detailed information than does a CAT scan about tumors and marrow cavities of the bone,
and can sometimes detect clusters of cancerous cells that have separated from the original
tumor. This valuable information helps surgeons select the most appropriate approach for
treatment.
- Radionuclide bone scans. These scans involve injecting a small amount of radioactive
material into a vein. Primary tumors or cells that have metastasized absorb the
radioactive material and show up as dark spots on the scan.
Cytogenic and molecular genetic studies, which assess the structure and composition of
chromosomes and genes, may also be used to diagnose osteosarcoma. These tests can
sometimes indicate what form of treatment is most appropriate.
Laboratory studies for Bone Cancer Diagnosis
A complete blood count (CBC) reveals
abnormalities in the blood, and may indicate whether bone marrow has been affected. A
blood test that measures levels of the enzyme lactate dehydrogenase (LDH) can predict the likelihood of a specific
patient's survival.
Immunohistochemistry involves adding special antibodies and chemicals, or stains, to
tumor samples. This technique is effective in identifying cells that are found in Ewing's
sarcoma but are not present in other malignant tumors.
Reverse transcription polymerase chain reaction (RTPCR) relies on chemical analysis of the
substance in the body that transmits genetic information (RNA) to:
- Evaluate the effectiveness of cancer therapies
- Identify mutations consistent with the presence of Ewing's sarcoma
- Reveal cancer that recurs after treatment has been completed.
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