Dysregulation of these processes by tumor cells leads to either osteoblastic or osteolytic lesions, reflective of the underlying mechanism of development.

[3] The most common sites of bone metastases are the spine, pelvis, ribs, skull, and proximal femur.

The microenvironment of differing bone types is thought to play a role in its predisposition to tumor seeding.

[15] The pathogenesis of bone metastasis via the vasculature is hypothesized to be related to the Batson vertebral vein plexus, a longitudinal valveless system connected to the breast, lung, kidney, thyroid, and prostate gland that extends from the sacrum to the skull.

[15] The triggers which eventually awaken metastatic tumor cells are an active field of study as they could elucidate mechanisms of controlling dormancy.

[15] Tumor cells may have paraneoplastic effects, such as via the secretion of prostaglandin E, TGF-alpha, TGF-beta, TNF, and interleukins to increase bone resorption.

[15] A combination of X-ray, CT and MRI scans may be most sensitive in the diagnosis of cancerous bone metastasis.

[15] However, these methods are less effective at identifying purely osteolytic lesions and will also highlight other areas of bone formation, such as those caused by trauma or inflammation unrelated to cancer.

Positron emission tomography (PET) with fluorine 18–labeled fluorodeoxyglucose ( 18 F-FDG) is a powerful diagnostic tool to visualize the activity of bone metastasis.

[15] Bone metastases on PET scan are usually multiple, irregularly distributed foci of increased tracer uptake without relationship to a single anatomic structure.

[15] Use of bone markers for detection and screening is an active field of research, though radiographic evidence remains the gold standard.

[15] However, once the presence of a bone metastasis has been established, tumor metabolic markers can provide useful diagnostic and prognostic information.

Orthopedic interventions such as internal fixation or spinal decompression may be necessary in the case of loss of structural stability due to bone destruction.

[20] Thermal ablation techniques are increasingly being used in the palliative treatment of painful metastatic bone disease.

[22][23] These studies are limited, however, to patients with one or two metastatic sites; pain from multiple tumors can be difficult to localize for directed therapy.