Ewing’s Sarcoma A Radiation Oncologist’s Perspective Professor Of Radiation Oncology Madras Medical College & Govt. General Hospital Chennai Prof. Mohan Ram R aroi - tn & pondicherry state conference-2006 Chennai 08 Jul’2006
“ the first indication is for treatment by radiation in full doses, and over considerable periods. This recommendation is based on the reported cure of certain cases….by radiation alone, and on the clinical disappearance of the disease by variable periods in many more cases. The response to radiation also confirms the diagnosis….”
In 75 – 90 % of Ewing’s sarcoma tumors the p53 dependant DNA damage apoptotic response pathway is largely intact.
Radio-responsiveness is possibly a contribution of the wild type p53, which is intact.
Kovar et al. Characterization of distinct consecutive phases in non-genotoxic p53-induced apoptosis of Ewing’s tumor cells and the rate limiting role of Caspase-8.Oncogene 2000; 19:4096-4107 Kovar et al. Response of Ewing’s tumor cells to forced and activated p53 expression. Oncogene 2003; 22: 3193-3204
Quality of the RT delivered in some negative trials is doubtful
e.g. Review of CESS-81 trial showed that there were major shortcomings in Volume delineation which accounted for high recurrence rates with RT, which when corrected subsequently improved results on par with Surgery in later CESS trials (e.g. CESS-86)
Surgical series always select patients at low-risk (e.g. Extremity lesions with low volume disease)
Second malignancies are related not to RT alone but to chemotherapy as well (Anthracyclines & alkylating agents)
Evidence for the Surgical bias
Interpretations for the Radiation Oncologist in decision making
Not all Studies are Strictly comparable, in fact no randomized study compares Surgery alone and RT directly.
Importance in practice should be attached to
- Relative functional deficits with RT Vs Surgery
Vs Surgery + RT
- Patient’s rehabilitation capacity
- Psychological adjustment of the patient
Surgery and RT are not competing modalities but are COMPLIMENTARY