Sarcoma

Question 1

RPS dose constraints

Answer 1

OARs:
Kidney bilateral mean dose <15 Gy (if both remain)
PMH: contralateral kidney mean dose less than 500cGy; ipsi Dmax less than prescription dose
Small bowel contoured as peritoneal cavity: V45Gy < 195 cc
Cord Dmax <48
Femoral head Dmax < 50Gy
Large bowel V50Gy< 40%

Question 2

Most likely to spread to lymph nodes

Answer 2

Clear cell
Angiosarcoma
Rhabdomyosarcoma
Epithelioid (ex: grade 1 always bad)

Question 3

IHC:
Desmin
S100
Cytokeratin
Factor VIII- related antigen

Answer 3

Desmin: rhabdo (think: rhabdo = column in latin like mm colum, desmin is also a thin muscle colum)
S100: nerve sheath tumor + clear cell (you just know this cause you’re smart)
Cytokeratin: epithelioid, synovial (you know cytokeratin is in the skin, like with epidermolyisis bullosa)
Factor VIII- related antigen: angiosarc, kaposi’s } think: factor 8 is in the blood: angio and kaposi - HIV is bloodborne illness

Question 4

What gene is amplified in a liposarcoma? (RC sample question)

Answer 4

MDM2
CDK4

Question 5

what is histologic grade determined by

Answer 5

mitoses, differentiation, necrosis (remember surgeon talking about this across from me in clinic, along with mitoses)

Question 6

Genetic syndromes associated with STS

Answer 6

NF1 (malignant peripheral nerve sheath tumor)
Familial retinoblastoma (Rb gene): STS, osteosarc, retinoblastoma
Li-Fraumeni: STS, osteosarc
Gardner’s (Subset of FAP): fibrosarcoma
Gorlin’s: fibrosarcoma, rhabdomyosarcoma (in addition to BCC, medulloblastoma)

Question 7

Mass in thigh, 2 most important structures to avoid and the consequences (RC sample question)

Answer 7

1) knee/hip: joint dysfunction of hip AVN
2) testes: infertility

Question 8

Benefits pre-op vs post-op XRT

Answer 8

Pre op:
- smaller XRT volume
- less toxicity bc lower doses
- Less joint fibrosis
- sterilize surgical area / prevent tumor seeding
- Decrease size of tumor

Post op:
- less wound healing issues
- Complete tumor specimen available for evaluation

Question 9

1) What is the gene fusion in clear cell sarcoma
2) Myxoid liposarcoma

Answer 9

1) EWSR1-ATF1 fusion (ew, stra1t for 1 node - because goes to nodes)
2) TLS-CHOP fusion (tiny little slxt, chop the CT! bc need whole body MRI)