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Osteosarcoma

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arunmp's version from 2016-12-16 10:59

REF:boris+santanu present+ icro hyderabad

Question Answer
epidemologybimodal distribution,black boys,mc radiation induced
Arise from multipotent mesenchymal cells
histopathosteoid
AssociationsLi-Fraumeni syndrome as well as retinoblastoma
classic versus juxta cortical interms of originclassic is from intramedullary and juxta cortical from outer surface of cortical bone
Two types of juxta corticallow grade para osteal and intermediate grade periosteal
Osteosarcoma radiology isusually sclerotic, involves the metaphysis, and has periosteal new bone formation (sunburst pattern)
Ewing sarcoma radiokogy lytic, located in the diaphysis, and displays an onionskin effect.
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TNM

Question Answer
T1≤8 cm
T2>8 cm
T3discontinuous tumors in primary bone site
N0no regional LN mets
N1regional LN mets
M0no DMs
M1aDMs to lung
M1bDMs to nonpulmonary sites
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Question Answer
standard Tx paradigm for conventional or highgrade osteosarcoma?preop chemo →surgical resection → adj chemo.
Define 3 roles for RT in the management of osteosarcoma.1. close or positive surgical margins that cannot be improved, 2. for surgically inoperable lesions(Difficult sites: Skull, spine and pelvis) 3. palliation of painful primary tumors in pts with metastatic Dz.4)extracorporeal radiation
What is the dose in Unresectable osteosarcoma (definite paradigm ) For unresectable Dz, a dose of at least 60–70 Gy
The preferred dose following an R2 resection is>55 Gy with boost to 64–68 Gy to the area of highest risk.
Radioisotope usedSamarium-153
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survival

Question Answer
The 5-yr survival for nonmetastatic osteosarcomatreated with chemo and surgery is60%–70%
For metastatic osteosarcoma, survival is ∼20%.
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Practical points

Question Answer
Tumor Necrosis more than --- are good responders90%
Neoadj setting what is role of RT role not defined
proximal tumors do ----than distal tumorsworse
Phase II CTV Volume LENGTHGTV +2-3 cms
Phase II CTV Volume width same as phase 1 (GTV + 2-3cm ion width,spare strip of skim)
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Dose : ref santanu presentation

Question Answer
60Gy in 30 fractions for microscopically involved margins
66 Gy in 33 fractions – macroscopic residual disease
70 Gy in 35 fractions – inoperable tumors
Single dose 50Gy to midplane, AP-PA, 6MVExtracorporeal irradiation (ECI)
20 Gy whole lung irradiation
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