Appropriate laboratory evaluation entails a complete blood count; metabolic panel that includes serum calcium and phosphorus, vitamin D, alkaline phosphatase, thyroid-stimulating hormone, and parathyroid hormone; and serum protein electrophoresis to rule out multiple myeloma.7,11 Tumor markers are useful to monitor a patient’s response to cancer treatment or to determine recurrence, but they play only a limited role in the initial work-up of an unknown bone tumor.28
Further imaging. A CT scan with intravenous contrast of the chest, abdomen, and pelvis is done to screen for visceral malignancy; however, 15% of bone lesions in patients with an unknown primary lesion never have a source identified.29 Bone scans can be useful in identifying the extent of a single lesion seen on plain films and to assess for additional asymptomatic lesions. Additional imaging—eg, CT or MRI of the lesion, or positron emission tomography (PET)—can be left to the discretion of the oncologist or surgeon.
CT scans have significantly higher sensitivity than radiographs and offer better visualization of bone quality, bone destruction, and soft-tissue extension.30 MRI can be used to assess changes in bone marrow and soft-tissue involvement. PET scans, which detect tumors by quantifying metabolic activity, remain controversial. PET is superior to bone scans in detecting bone metastases from lung and breast cancers, but worse in renal and prostate cancers due to slow growth of metastases.31-33
Caveat. Do not assume that a bone lesion is metastatic. Delayed diagnosis of a primary bone tumor can lead to significant changes in clinical course and patient outcome.34 If any doubt exists as to the type of lesion, arrange for a biopsy using proper technique and delay bone fixation until a histologic diagnosis is complete.35 Biopsy may be performed via image-guided fine-needle aspiration, core biopsy, or open incisional biopsy.
Metastatic bone disease is typically managed nonsurgically with radiation, chemo- or immunotherapies, hormone suppression, bone-modifying agents, or ablation.36 An overview of the cancer treatment guidelines for bone metastasis from the 2017 National Comprehensive Cancer Network is shown in TABLE 2.36
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