ESTRO 2024 - Abstract Book

S2100

Clinical - Sarcoma, skin cancer, melanoma

ESTRO 2024

1562

Digital Poster

Radiotherapy for rhabdomyosarcoma in Adolescents and Young Adults compared to children

Karin M. Meijer 1 , Arjan Bel 1 , Winette T.A. van der Graaf 2,3 , Olga Husson 2,4,5 , Brian V. Balgobind 1 , Irma W.E.M. van Dijk 1

1 Cancer Center Amsterdam, Amsterdam UMC, University of Amsterdam, Radiation Oncology, Amsterdam, Netherlands. 2 Netherlands Cancer Institute-Antoni van Leeuwenhoek, Medical Oncology, Amsterdam, Netherlands. 3 Erasmus MC Cancer Institute, Erasmus University Medical Center, Medical Oncology, Rotterdam, Netherlands. 4 Netherlands Cancer Institute, Psychosocial Research and Epidemiology, Amsterdam, Netherlands. 5 Erasmus MC Cancer Institute, Erasmus University Medical Center, Surgical Oncology, Rotterdam, Netherlands

Purpose/Objective:

Adolescent and Young Adult (AYA) cancer patients, aged between 18 and 39 years at primary diagnosis, form a unique oncological group. Rhabdomyosarcoma (RMS) is considered a typical childhood cancer, but can occur at any age. Since no adult-specific treatment protocols are available, AYAs diagnosed with RMS are often treated according to pediatric protocols. For children, the overall 5-year survival rate has increased up to 70%, but the prognosis for (young) adult RMS patients is less satisfactory with 5-year overall survival rates of 20-40% 1,2 . The clinical management of AYA patients presenting with RMS is challenging due to delayed diagnosis, less favorable clinical presentation, higher frequency of metastatic disease, and poorer tolerance to treatment 2 – 4 . Radiotherapy is a key element in treatment of RMS, but literature on radiotherapy in AYAs is scarce compared to children. Therefore, the aim of this study is to describe the patient demographics, treatment protocols and radiotherapy parameters of AYAs treated for RMS, and to compare those with children.

Material/Methods:

For this retrospective descriptive cohort study, we included a sample of twelve AYAs (i.e. 52% of the total RMS cohort) and twelve children (<18 years) diagnosed with RMS, who were treated with radiotherapy between 2000 and 2020 at our radiotherapy department. For both subcohorts, data regarding clinical and tumor characteristics (e.g. tumor location, histology, metastatic disease), treatment protocols and modalities, and 5-year survival rate were extracted from health records. Furthermore, radiotherapy parameters such as number of fractions, fraction and total dose, and acute toxicity were evaluated. The results are presented as descriptive statistics.

Results:

The patient characteristics of both subcohorts are shown in Table 1. The median age of the AYA patients at start of radiotherapy was 23.7 years, with a range of 18.3 – 33.4 years. The median age of the children was 9.1 years, with range 3.1 – 17.5 years. Most AYA patients (8/12; 75%) presented with an alveolar RMS, and most children (8/12; 75%) with an embryonal RMS. In both AYAs and children, the most common primary tumor location was the head-and neck area. At the time of diagnosis, four AYAs (33%), and three children (25%) presented with lymph node metastases, and four AYAs (33%) and two children (17%) with distant metastatic disease. All children were treated according to the EpSSG 2005 RMS protocol. The inclusion criteria for this clinical trial protocol was <21 years, however, also all AYA patients were treated according to this protocol, regardless of their age.