Palliation of Bone Metastases Flashcards
Bone Metastases
What are the most common cancers which metastasize frequently to bone?
breast and prostate (70%)
lung…
others: thyroid, melanoma, kidney
rare: GI
Bone Metastases
What are the most common sites?
axial skeleton
spine particularly (lumbar), pelvis, and ribs
Bone Metastases
What is the most commonly involved part of the appendicular skeleton?
proximal femurs
Bone Metastases
Pathophysiology
All of the following are true, EXCEPT?
I. Osteoblasts originate from osteogenic cells, found in
the periosteum or endosteum.
II. The cells differentiate into osteoblasts when there is a mechanical or chemical stimulus for remodeling or repair.
III. The osteoblasts build bone by depositing collagen type II into the extracellular space.
IV. An inorganic complex of calcium and phosphate (hydroxyapatite) is laid down
within this organic matrix to provide the strength and density of the bone.
V. The osteoblasts then mature into osteocytes, which maintain the bone structure.
III.
collagen type I
Bone Metastases
Pathophysiology
Osteoclasts are multinucleated giant cells that originate from osteogenic progenitor cells and adhere to the bone surface.
These cells
create an acidophilic environment that causes dissolution of the hydroxyapatite
crystals and proteolysis of the bone matrix.
TRUE or FALSE?
False
***
originate from pluripotent
hematopoietic bone marrow
Bone Metastases
Pathophysiology
All of the following are true, EXCEPT?
I. The RANKL on osteoblasts binds to the RANK receptor on osteoclast
precursors, which then induces the formation of mature osteoclasts.
II. Osteoprotegerin is a decoy receptor for RANKL and
inhibits the differentiation and activation of osteoclasts.
III. The destruction of
bone by osteolytic metastases does not involve the osteoclasts and is directly mediated by tumor cells
III. The destruction of
bone by osteolytic metastases is mediated by the osteoclasts, not by the tumor
cells. However, the factors that activate the osteoclasts are likely produced by the
tumor cells, including RANKL, interleukin-1, interleukin-6, parathyroid
hormone-related peptide (PTHrP), transforming growth factor β (TGF-β), and
macrophage inflammatory protein 1α.
Bone Metastases
Normal bone is constantly being remodeled in a cycle.
How long is a normal bone cycle?
120-200 days
For the first 20 to 40 days of the cycle, the bone is
resorbed by osteoclasts. The bone is then rebuilt by osteoblasts during the next
100 to 150 days
Bone Metastases
What malignancy/tumor is associated with purely
osteolytic lesions?
myeloma
Bone Metastases
Bone scintigraphy is an indicator of osteoblastic activity and therefore may give false-negative readings in highly-aggressive tumors if the lesions are mainly osteolytic.
TRUE or FALSE?
True.
Bone Metastases
When using plain radiographs, it is important to bear in mind that approximately __to__% of the bone mineral content must be lost before the lesion will be apparent on x-rays.
Approximately 30% to 50% of the bone mineral content must be lost before the lesion will be apparent on x-rays.
Bone Metastases
All of the following are true, EXCEPT?
I. CT may be useful in defining the extent of cortical destruction and helping to assess the risk of a pathologic
fracture.
II. CT scan may be used to guide needle biopsies to
obtain a tissue diagnosis
III. CT scan’s ultimate value is its usefulness in
detecting marrow involvement and are much better than plain radiographs at
evaluating soft tissue extension of disease.
III.
It’s of lesser usefulness for detecting marrow involvement.
Bone Metastases
All of the following are true, EXCEPT?
I. Magnetic resonance imaging (MRI) is no better than plain radiography or
nuclear medicine bone scintigraphy at assessing the involvement of trabecular
bone and bone marrow, especially in the vertebral bodies
II. MRI scans are useful in determining the
involvement of neurovascular structures.
III. MRI images can help distinguish whether a vertebral body compression fracture is from malignancy or from osteoporosis.
I
***
Magnetic resonance imaging (MRI) is better than plain radiography or
nuclear medicine bone scintigraphy at assessing the involvement of trabecular
bone and bone marrow, especially in the vertebral bodies.
The findings are typically best seen on T1 contrast-enhanced images and shorttau
inversion recovery (STIR) images. Metastatic prostate cancer is visible as
high-intensity lesions on the STIR images and is visible prior to its appearance
on bone scintigraphy.
In addition, MRI scans are useful in determining the
involvement of neurovascular structures. MRI scans are not useful as a screening
tool for bone metastases because of the high cost and lengthy time of the exam.
However, MRI scans may be more sensitive than bone scintigraphy in the
vertebral body region. The sensitivity of MRI scanning has been reported as
91% to 100%, compared with 62% to 85% for bone scintigraphy.
In
addition, MRI images can help distinguish whether a vertebral body
compression fracture is from malignancy or from osteoporosis.
Bone Metastases
Which is more FDG avid? osteolytic or osteoblastic?
lytic.
in contrast to bone scan where blastic lesions are seen better than lytic.
Pain Management
What are the three steps of the WHO analgesic ladder?
step 1 - nonopioid (acetaminophen, NSAIDs)
step 2 - weak opioid (codeine)
step 3 - strong opioid (morphine and oxycodone)
Bone Metastases
Which bone has the propensity to cause morbidity and functional deficits due to fracture risk, necessitating surgical internventions?
pretrochanteric (proximal) femur
65% requires surgical intervention
Bone Metastases
What is the measurement usually predictive of pathologic fracture? (plain radiograph)
≥2.5 cm in the cortex
