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Palliation of Metastases

Epidemiology. Osseous metastases is the most common cause of intractable pain in cancer patientsThird common site of spread after lung and liverPresentation occurs after primary diagnosis in majority of patientsBut in 23% of patients it is the presenting problem which leads to the discovery of di

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Palliation of Metastases

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    1. Palliation of Metastases Iftekhar Ahmad, MD Wayne State University/KCI July 8thth, 2008

    2. Epidemiology Osseous metastases is the most common cause of intractable pain in cancer patients Third common site of spread after lung and liver Presentation occurs after primary diagnosis in majority of patients But in 23% of patients it is the presenting problem which leads to the discovery of disease

    3. Pathophysiology Tumor cells primarily gain access to the circulation through the capillaries 1). Release of tumor cells from the primary 2). Invasion of vascular or lymphatic channels 3). Dissemination to distant sites 4). Endothelial attachment and invasion of new host 5). Growth into a metastatic focus

    4. Pathophysiology Skeletal blood flow accounts for only 4-10% of total cardiac output Incidence of skeletal metastases appears higher than expected Microstructure of marrow renders it vulnerable to tumor accumulation and invasion Arteries tend to divide capillaries as they near the endosteal margin of bone Capillaries become continuous with venous system which has a 6-8 times capacity The circulation comes to a near standstill at this point potentially allowing tumor cells more time to invade

    5. Pathophysiology Tumor angiongenesis factor attracts vessels to a small tumor colony Otherwise it would be dependant on local tissue circulation and incapable of further invasion The production of this factor is partially blocked by immune responses so it may take years to have adequate vasculature for invasion

    6. Mediators Some tumors produce and secrete humeral mediators that stimulate osteoclast activity: TGF PDGF TNF Prostaglandins Interleukins

    7. Distribution More prevalent in the axial skeleton versus the appendicular skeleton But richer blood flow in appendicular skeleton would predict higher rates

    8. Imaging Plain X-rays are the fastest form of imaging Medulla involved early and cortex late Role for patients with pain and positive bone scan to uncover pathologic fractures Sclerotic: Prostate, Breast, GI, Bladder Lytic: All sites Mixed: Breast More than 50% cortical destruction needed to detect

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