Intra-operative extracorporeal radiation therapy for skeletally immature patients with malignant bone tumours

ABSTRACT BACKGROUND: Management of malignant bone tumours has changed dramatically in recent years. Neoadjuvant chemotherapy, irradiation and conservative surgery have improved local control as well as functional outcome. Depending on the histology of the lesion, other modalities like chemotherapeutic agents or radiation can be selected in place of surgical intervention. Operative intervention is the main modality with wide marginal excision and fixation of bone graft from different sources or mega prosthesis to maintain congruity of the bone anatomy. Reconstruction, optimum fit and stability at the affected site are the major areas of concern with this modality. Radiation given outside the body to kill the tumour cells in the bone is called extracorporeal radiotherapy (ECRT). After resection of the bone, it is cleaned of all the surrounding soft tissue and marrow contents and placed in a container. It is then subjected to 50 Gy of radiation which kills all the tumour cells. METHODS: The study was conducted from June 2014 to May 2020, and included 15 patients (out of 18) diagnosed with either Ewing's sarcoma or osteosarcoma. They were followed up for an average of 4.44 years, up to May 2020. All 15 cases were analysed for bony union at the osteotomy sites. Cases reported with poorly differentiated sarcomas (total three) were subjected to immunohistochemistry and managed with other modalities of treatment. RESULTS: The average time for union of irradiated bone was 8.1 months (range 5-10; the metaphyseal end united faster than the diaphyseal end). At the final follow-up, the functional status was determined using the Musculoskeletal Tumour Society (MSTS) scoring system. Ninety-three per cent of patients had involvement of the lower limb (14 out of 15). All patients (except one who developed recurrence) did not have symptoms of the disease and no one had died at last follow-up. CONCLUSION: Biological limb salvage procedures are considered a successful treatment and a welcome alternative for patients who either cannot afford or be treated with an endoprosthesis. Early diagnosis and referral to specialised unit is of vital importance. This procedure can be used for selected patients with malignant bone tumours. Cost factors, and social and cultural considerations also play a role Level of evidence: Level 4. Keywords: ECRT, extracorporeal radiation therapy, malignant bone tumours, bone sarcoma, osteosarcoma, Ewing's sarcoma