CRO Exam 2 Questions & Answers 2024/2025
What is the age range of most cases of bone tumors and why do most cases occur during this age range? - ANSWERS10-20yrs of age [60%]
(most active age of skeletal growth)
What is the hallmark of osteosarcoma? - ANSWERSmalignant osteoid
What is the...
What is the age range of most cases of bone tumors and why do most cases occur during this age range?
- ANSWERS10-20yrs of age [60%]
(most active age of skeletal growth)
What is the hallmark of osteosarcoma? - ANSWERSmalignant osteoid
What is the most common bone tumor in children? - ANSWERSOsteosarcoma
When treating bone tumors in an extremity with radiation therapy, why is a 1.5-2
cm strip of skin left out of the field? - ANSWERSTo prevent lymphedema
hen constructing a field to treat a bone tumor with radiation therapy, what is included in the field and
what margin is added? - ANSWERSInclude entire surgical bed + scar + 2 cm margin if possible
What are the dose limitations to consider when using radiation therapy to treat bone tumors? -
ANSWERS>20 Gy can prematurely close epiphysis
>40 Gy will ablate bone marrow
>50 Gy to bone cortex significantly increases risk of bone fracture
30 Gy Dmax to cord and brainstem for 5-fraction SBRT
7. What are the possible complications for treating bone tumors with radiation therapy? -
ANSWERSAbnormal growth, weakened bone, scoliosis, decreased range of motion, vascular changes,
fracture, lymphedema, skin discoloration or telangiectasia, osteoradionecrosis
,also risk of secondary cancers
Where in the body do soft tissue sarcomas most frequently occur? - ANSWERSLower extremity (45%)
trunk (30%)
visceral (19%)
retroperitoneal (15%)
H&N (8%)
What is the typical presentation for a soft tissue sarcoma and what is the usual time frame from
symptoms to diagnosis? - ANSWERSPainful mass, 6 months
Where do soft tissue sarcomas in the extremity metastasize to? - ANSWERSlung
What margin is given in a wide en bloc surgical resection for soft tissue sarcoma? - ANSWERS2cm
margins in all directions
In which direction should surgical scars to remove a soft tissue sarcoma be oriented and
why? - ANSWERSlongitudinally
so circumferential RT can be avoided
Why are surgical clips placed during surgery to remove a soft tissue sarcoma? - ANSWERSFor RT planning
Why should post-op external beam radiation therapy (post-op EBRT) be administered
, following surgery and how soon? - ANSWERSStart 10-20 days after surgery for healing
What beam energies are used to treat soft tissue sarcoma in the extremities? - ANSWERS4-6MV
When constructing a radiation field for post-op external beam radiation therapy (post- op EBRT) to treat
soft tissue sarcoma, what is included in the field and what are the margins (describe primary field and
boost)? - ANSWERSField = tumor bed, scar, drainage sites +4 cm longitudinally and 1.5 cm perpendicular
margin in initial field. After 50 Gy, reduce field to surgical bed (outlined by clips, scar) + 2 cm margin. Add
1 cm to PTV.
How should the patient be positioned to simulate a soft tissue sarcoma in the: - ANSWERSUpper inner
thigh - frog-leg position
Buttock/post thigh - prone position
If surgery is to follow radiation therapy for soft tissue sarcoma, when after radiation should surgery be
given? - ANSWERS3 weeks after RT
Do wound complications occur more frequently with post-op RT or pre-op RT done for
soft tissue sarcoma? - ANSWERS5-15% with post-op RT vs 25-35% with pre-op RT
What type of cells give rise to sarcomas? - ANSWERSMesenchymal cells, which can develop into bone,
cartilage, fat, muscle, etc.
Describe the epidemiology and presentation of sarcoma. - ANSWERS16,000 new cases/yr. Commonly
found in adults ages 40-60, more often among men. Risk factors are relatively fuzzy and could include
genetics, prior RT, and immunodeficiency. Often develops in the extremities, though it can appear
anywhere. Usually presents as a painless mass. 20-25% of cases have distant mets at presentation.
How do sarcomas grow? - ANSWERSAlong the path of least resistance, i.e. along the length of a muscle
but not across its width.
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