Ewing's Flashcards
why does ewings peak in 10-20 yrs
rapid bone growth during puberty
can ewings be inherited?
no
difference between intracompartmental and extracompartmental
bone tumors confined within the cortex of the bone
bone tumours extend beyond the bone cortex
Stage 1A means?
low grade intracompartmental
stage 2B
high grade extracompartmental
what is lactic dehydrogenase
enzyme that helps produce energy
increased levels are associated with cell damage and can signify tumour activity
why is it preferred to start with induction chemo
to see how effectiveness
shirk tumour as much as possible
bone healing may take place lowering risk of patho fracture
why is it important to shrink tumour first
can decrease the vol of RT
better chance at negative margins
if surgery not indicated then what is the plan?
RT and then chemo
surgery is optimal
for small tumours on expendable bones what is the probable care path
RT or surgery
for large unresectable tumours what is the probable care path
debulking surgery followed by RT
what pt factors does surgery depend on
tumour location
age
other tx
extent of disease
what is probable if RT fails for a tumour on an extremity
amputation
what are 3 surgical options for pts with tumours of the distal femur
complete amputation
lumb salvage
rotationplasty
when is RT treatment of choice
unresectable tumour post op + margins distal extremity lesions in nonexpendable bones pelvis and spine tumours impending pathological fracture met disease BMT
total dose to GTV (coned down)
5580
pre chemo dose
4500
6000 cGy has similar control than standard doses why dont we use 6000 then?
because it showed a notable increase in secondary malignancies
what is the margin added to GTV1 to make CTV1
1.5cm
what is the margin added to CTV1 to make PTV1?
0.5-1cm
usual dose is 4500/25
if pathologically involved LN are present what is the dose
PTV1 will receive 5040/28
what structures/tissues are inv with GTV2
all pretreatment bony involvment, post chemo soft tissue disease, residual primary disease after preop RT and surgery, unresected LN
what is the margin added to GTV2 to make CTV2?
1cm
what is the margin added to CTV2 to make PTV2
0.5-1cm
dose usually 540/3fx
why is there GTV1 and GTV2
2 indicated boost
what is typical dose to PTV1 and PTV 2? total?
5040cGy
540cGy
total 5580
what are the conventional fields sizes
all bony disease +2cm margin+soft tissue extension with margin
must spare uninvolved regions of soft tissue at edges to avoid lymphedema (1cm strips)
effects of RT on femur
2/3 pts develop shortening of 2cm or more
1/3 develop pathologic fractures
