Radio resistant tumor among the following is:
a. Osteogenic Sarcoma
"The inherent radiation resistance of osteogenic cells, with their marked ability to repair radiation damage, necessitates doses of the order of 70 to 80 Gy to obtain local control.
The soft tissue and bone morbidity from such high radiation doses has essentially precluded the use of radiation therapy for primary treatment of osteogenic sarcoma."
b. Ewing's Sarcoma
"Ewing's sarcoma may seem to the patient to be localized, as far as the oncologist is concerned, the problem is of systemic control.
Ewing's sarcoma is highly responsive to both chemotherapy and radiation, and the lowered metastatic rate and improved survival with the introduction of adjunctive chemotherapy has been one of the success stories of combined modality treatment."
i. The earliest stage of neuroblastoma, patients receive initial chemotherapy (Cyclophosphamide, cisplatin, doxorubicin) followed by surgery and adjuvant radiotherapy.
ii. Note: Spontaneous regression is seen in neuroblastoma.
iii. Wilm's Tumor
iv. Treatment consists of nephrectomy as soon as possible, followed by radiotherapy with or without chemotherapy.
Most radioresistant tumors
1. Malignant melanoma
3. Pancreatic carcinoma