Most radiosensitive bone tumor is
Correct Answer: Ewing's sarcoma
Description: Ans. a (Ewing's sarcoma). (Ref. Essential Orthopedics by Maheshwari, 2nd ed., 220; Harrison 18th/ch. 98)Osteosarcoma is relatively radioresistant and wide surgical resection and chemotherapy is the RX. There is no role of RT in Rx of Aneurysmal bone cyst and Chondroblastoma.EWING'S SARCOMA# Ill-defined osteolytic medullary lesion involving diaphysis.# Small round cell PNET tumor.# Age group 5-15 years with 75% patients being under the age of 20 years and having male predilection.# Extension along the length of the marrow with permeative bone destruction.# Cortical saucerization.# Classical multilaminar periosteal reaction giving 'onion-peel' appearance.# Codmann's triangles with elevated periosteum.# Soft tissue mass disproportionately large compared to the extent of osseous involvement, resembling osteomyelitis.# Bone tumor metastasizing to bone.# Ewing's sarcoma is the highly malignant primary bone neoplasm having specific cytogenetic analysis i.e. t( 11,22), is a PNET.# CD99 is important marker# It is thought to be radiosensitive bone tumor, and supposed to melt with radiotherapy. However, Chemotherapy is the mainstay of treatment for Ewing's primitive neuroectodermal tumors (PNET) and rhabdomyosarcomas.External beam radiation therapy is an adjuvant to limb-sparing surgery for improved local control. Preoperative radiation therapy allows the use of smaller fields and smaller doses but results in a higher rate of wound complications. Postoperative radiation therapy must be given to larger fields, as the entire surgical bed must be encompassed, and in higher doses to compensate for hypoxia in the operated field. This results in a higher rate of late complications. Brachytherapy or interstitial therapy, in which the radiation source is inserted into the tumor bed, is comparable in efficacy (except in low- grade lesions), less time-consuming, and less expensive. Although Ewing's sarcoma is radiosensitive, systemic chemotherapy is the mainstay of therapy, often being used before surgery. Doxorubicin, cyclophosphamide or ifosfamide, etoposide, vincristine, and dactinomycin are active drugs. Topotecan or irinotecan in combination with an alkylating agent are often used in relapsed patients. Targeted therapy with an anti IGF 1 alpha antibody appears to have promising activity in refractory cases. Local treatment for the primary tumor includes surgical resection, usually with limb salvage or radiation therapy.
Category:
Radiology
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