Background: Denosumab represents a valuable treatment option for unresectable giant cell tumors of the bone (GCTBs). However, no standardized protocols exist determining the length of administration, with few studies having been published on patients who reached the end of treatment.Aims: To analyze the outcomes of patients diagnosed with GCTB and who had finished single treatment with denosumab.Methods and Results: This is a multicenter, retrospective, descriptive study carried out in seven Spanish hospitals with multidisciplinary sarcoma and musculoskeletal tumor boards, between 2009 and 2019. Sixteen patients diagnosed with unresectable GCTBs and treated with denosumab who had reached the end of their treatment were recruited for the study and had been followed up for a minimum of 2 years. Fifty percent of patients discontinued denosumab after showing signs of tumor control. The disease remained stable in 69% of patients (n = 11), with a median recurrence‐free survival time of 46 months (20–157 months) after being treated for a median period of 19 months (5–83 months). Four patients experienced local progression, and one presented multifocal progression. These five patients were treated for a median period of 46 months (14–76 months), with a median recurrence‐free survival time of 9 months (5–25 months).Conclusion: The findings of the present study suggest that discontinuation of denosumab in patients with unresectable GCTB is not necessarily associated with the progression of the disease. Further research is needed to determine how long denosumab should be administered to minimize the risk of recurrence.

Objective The objective of this study was to perform an epidemiological analysis of patients presented to the Musculoskeletal Tumors Committee of a reference hospital. Material and method A retrospective analysis of patients with sarcomas treated in a reference Sarcoma Unit between 2009 and 2022 was carried out. Results A total of 1978 patients were analyzed, of which 1477 (74.67%) were diagnosed as sarcomas. They were divided into 446 (30.20%) bone tumors and 1.031 (69.80%) soft tissue tumors. The most common benign bone tumor was enchondroma (27.23%), giant cell tumor (59.21%) was the most common tumor of intermediate malignancy and the malignant one was osteosarcoma (24.78%). The most frequently observed benign soft tissue tumor was lipoma (50.74%), the atypical lipomatous tumor (53.25%) was the most frequent tumor of intermediate malignancy and the malignant one was sarcoma of uncertain differentiation (38.10%). Conclusion Our study represents the first work on the epidemiology of sarcomas and other musculoskeletal tumors in our country, being very useful to adapt the resources destined for their diagnosis and treatment.

Introducción: El rabdomiosarcoma en adultos es un tumor poco frecuente que tiene una supervivencia inferior en comparación con la población pediátrica. El objetivo es realizar una revisión retrospectiva de los pacientes adultos intervenidos en nuestro centro de rabdomiosarcoma para analizar la epidemiología y la supervivencia. Materiales y métodos: Se realizó un análisis retrospectivo observacional de 29 pacientes adultos (>16 años) diagnosticados con rabdomiosarcoma en nuestro centro entre los años 2009 y 2024. Resultados: 20 pacientes presentaron enfermedad localizada con una edad media de media de 33,9 años (rango 17 - 78) y un 70% mujeres; mientras que 9 presentaban enfermedad diseminada con una edad media de 33,67 años (rango 18 - 66) y 55% mujeres. El sitio más común fueron las extremidades (55,17%) y el subtipo histología mayoritario fue el rabdomiosarcoma alveolar (45%). El 55% de los pacientes (n = 11) con enfermedad localizada fueron intervenidos sin criterios oncológicos en otros centros. El 25% de los pacientes con enfermedad localizada sufrieron una recaída local, observando una relación estadísticamente significativa entre los márgenes obtenidos y la recidiva local (p = 0.0087). El 45% de los casos sufrieron una recaída sistémica, siendo la mediana de seguimiento de 33,5 meses (rango 1-11). La supervivencia global es 37,93%, teniendo una menor supervivencia aquellos pacientes que presentaban metástasis en el diagnóstico (p= 0.005). Conclusión: El rabdomiosarcoma en adultos tiene un peor pronóstico que el rabdomiosarcoma pediátrico. Se requiere un equipo multidisciplinar especializado y una estandarización del régimen de tratamiento en este tipo de patologías.