RADIATION INDUCED SARCOMAS OF BONE: FACTORS THAT AFFECT OUTCOME

Aim To identify patient, tumour or treatment factors that influence outcome in patients with radiation induced sarcoma of bone. Method A retrospective review of an oncology database supplemented by referral back to original records. Results We identified 42 patients who presented to our Unit over a 25 year period with a new sarcoma of bone following previous radiotherapy. The age of the patients at presentation ranged from 10 to 84 years of age (mean: 17 years) and the time interval from previous radiotherapy ranged from 4 to 50 years (median: 14 yrs; mean: 17 years). The median dose of radiotherapy given had been 50 Gy but there was no correlation of radiation dose with time to development of sarcoma. The pelvis was the most common site for development of sarcoma (14 cases) but breast cancer was the most common primary tumour (8 cases). 9 of the patients had metastases at the time of diagnosis of the sarcoma. Osteosarcoma was the most common diagnosis (30). Treatment was by surgery and chemotherapy when indicated and 30 of the patients had treatment with curative intent. The survival rate was 41% at 5 years for those treated with curative intent but in those treated palliatively median survival was only 6 months and all had died by one year. The only factor found to be significant for survival was the ability to completely resect the tumour; thus, limb sarcomas had a better prognosis (66% survival at 5 years) than central ones (12%)(p=0.009). Conclusion Radiation induced sarcoma is a rare complication of radiotherapy. Both surgical and oncological treatment is likely to be compromised by previous treatment the patient has received. Despite this 40% of patients will survive more than 5 years with aggressive modern treatment.