Oncology Flashcards
(39 cards)
osteosarcoma most commonly arises from…
from metaphyseal region of long bones of the appendicular skeleton
osteosarcoma most common sites are…
distal femur
proximal tibia
proximal humerus
these are the most rapidly growing sites of the body and are at highest risk for malignant transformation
some cases of osteosarcoma are associated with tumor suppressor genes (autosomal *** inheritance) including:
Dominant
Retinoblastoma (Rb)
P53 (Li-Graumeni syndrome)
Conditions associated with osteosarcoma
- Retinoblastoma
- Li-Fraumeni Syndrome (breast CA + osteosarcoma)
- Rothmund-Thomson (AR, RECQL4 gene, sun sensitive facial rash, alopecia, cataracts, dental abnormalities, several cancers)
- Bloom Syndrome (AR, BLM gene, uv-induced facial rash, short stature, IR, scant subs fat, several tumors)
- Werner Syndrome (AR, WRN gene, premature aging, osteoporosis, cataracts)
- Fibrous dysplasia
*** is most common site of osteosarcoma metastasis. 2nd most common?
lung, bone
patients can also present with synchronous bone lesions without pulmonary metastases, this is called
multicentric osteosarcoma
2 kinds of skip mets
intraosseous skip metastases: within the same bone, usually proximal to the main tumor
trans-articular skip metastases: cross the joint
osteosarcoma subtype classifications
- intramedullary
- high-grade: conventional osteosarcoma, telangiectatic osteosarcoma, small-cell
- low-grade: fibrous dysplasia-like, desk-plastic fibroma-like - surface
- high-grade: dedifferentiated surface
- intermediate: periosteal osteosarcoma (between surface of bone and inner layer of periosteum)
-low: parosteal osteosarcoma (from outer layer of periosteum) - intracortical–rarest type of bony
- extra skeletal–rarest subtype, considered soft tissue sarcoma
Osteosarcoma XR findings
medullary and cortical bony destruction, usually soft tissue mass, periosteal rxn (codman’s triangle). usually mixed blastic/lytic
What other imaging should be obtained on presentation of osteosarcoma?
CT chest
no clear role for PET
what labs indicate more severe dz in osteosarcoma?
LDH, ALP
conventional intramedullary osteosarcoma.
Histologic description of conventional intramedullary osteosarcoma
Tumor cells produce “lacey” osteoid
Stroma appear malignant with high nucleus-to-cytoplasm ratio, abnormal mitotic figures
conventional intramedullary osteosarcoma tx
wide resection + chemo
in the setting of pathologic fx through conventional intramedullary osteosarcoma, can undergo limb salvage if …
the fracture is stabilized throughout neoadjuvant chemotherapy (ex-fix or cast)
standard chemotherapy for conventional intramedullary osteosarcoma
methotrexate, doxorubicin (adriamycin), cisplatin, +/- ifosfamide.
preoperative (neoadjuvant chemotherapy) given for 8-12 weeks followed by maintenance chemotherapy for 6-12 months after surgical resection
indications for rotationplastly osteosarcoma
sarcomas of the hip, femur, knee, proximal tibia
failed limb salvage with intact distal leg
proximal femoral focal deficiency (PFFD)
goal is to have the rotated ankle at the same level of the contralateral knee at skeletal maturity
***% necrosis after neo-adjuvant chemotherapy is good prognostic sign
> 90%
resection surgical algorithm
if restaging suggests that lesion is resectable, then perform wide excision
positive margins:
good response to preoperative chemo (<10% viable tumor on postop pathology; >90% tumor necrosis)–>continue same neoadjuvant chemo regimen, consider additional resection +/- radiation
inadequate response to preoperative chemo (>10% viable tumor on postop pathology; <90% tumor necrosis)–>consider alternative neoadjuvant chemo regimen, additional resection +/- radiation
negative margins:
good response to preoperative chemo (<10% viable tumor on postop pathology; >90% tumor necrosis )
continue same neoadjuvant chemo regimen, no further resection required
inadequate response to preoperative chemo (>10% viable tumor on postop pathology; <90% tumor necrosis)
continue same neoadjuvant chemo regimen or consider alternative regimen, no further resection required
why is osteosarcoma radioresistant?
JNK-mediated cellular apoptosis is a known cellular mechanism in response to ionizing radiation
osteosarcoma routinely expresses NFkB, which is an INHIBITOR of the JNK radiation-induced apoptosis pathway and is thus a radioresistant tumor
what is an indication for radiation in osteosarcoma?
usually reserved for palliative control in inoperable primary tumors, metastatic sites or after resection of selected tumors with close margins especially pelvic and spine tumors. extraskeletal osteosarcoma is an exception, which is radiosensitive with reduced local recurrence rates
conventional osteosarcoma prognosis
without detectable metastases at the initial presentation
approximately 65% with standard treatment of pre/post-operative chemotherapy and wide resection
85% with good response to preoperative chemotherapy
65% with localized osteosarcoma in an extremity
55% with localized pelvic osteosarcoma. pelvic disease inherently more aggressive
approximately 15-20% with detectable pulmonary metastases at initial diagnosis
patients who present with or develop pulmonary mets can often be treated with pulmonary metastatectomy
bone metastases are considered incurable
Most common benign bone tumor:
osteochondroma
solitary osteochondromas can arise because of…
Salter-Harris fracture
surgery
radiation therapy (commonest benign radiation-induced bone tumor)
