Radiotherapy for bony manifestations of Langerhans Cell Histiocytosis. Review and proposal for an international registry

Purpose: to examine the role of radiotherapy (RT) in adult Langerhans Cell Histiocytosis (LCH) for osseous manifestations, to define open questions regarding RT, and to develop recommendations for the clinical decision-making and problem-solving process. Material and methods: a literature review using different medical databases was conducted including the last 3 decades, and resulting questions regarding the use of ionizing radiation were systematically compiled. Results: the literature review revealed a local control rate of 96% (93% complete remissions) in patients with osseous single-system disease and of 92% (76% complete remissions) in patients with bony involvement in multi-system disease. To increase our knowledge, a prospective registry has been developed to allow a differentiated analysis of RT outcome and definition of potential prognostic factors. Conclusion: ionizing radiation can be successfully applied as a single treatment or in combination with other therapies for osseous manifestations of LCH. It leads to high remission and local control rates. Nevertheless, many open questions still exist. A prospective clinical registry is proposed to define the exact role of RT in this disease and to develop future interdisciplinary treatment guidelines. (orig.)