Adolescents and young adults with rhabdomyosarcoma treated in the European paediatric Soft tissue sarcoma Study Group (EpSSG) protocols: a cohort study

Background: Adolescent and young adult patients with rhabdomyosarcoma often have poorer outcomes than do children. We aimed to compare the findings of adolescent and young adult patients with children enrolled in two prospective clinical protocols. Methods: This retrospective observational analysis was based on data from the European paediatric Soft tissue sarcoma Study Group (EpSSG) rhabdomyosarcoma 2005 trial (phase 3 randomised trial for localised rhabdomyosarcoma, open from April, 2006, to December, 2016) and the EpSSG MTS 2008 protocol (prospective, observational, single-arm study for metastatic rhabdomyosarcoma, open from June, 2010, to December, 2016), which involved 108 centres from 14 different countries in total. For this analysis, patients were categorised according to their age into children (age 0–14 years) and adolescents and young adults (age 15–21 years). For the analysis of adherence to treatment and toxicity, only patients with high-risk localised rhabdomyosarcoma included in the randomised part of the rhabdomyosarcoma 2005 study were considered. The primary outcome of event-free survival (assessed in all participants) was defined as the time from diagnosis to the first event (eg, tumour progression, relapse) or to the latest follow-up. Secondary outcomes were overall survival, response to chemotherapy, and toxicity. Findings: Our analysis included 1977 patients, 1720 children (median age 4·7 years; IQR 2·6–8·4) and 257 adolescents and young adults (16·6 years; 15·8–18·0). 1719 patients were from the EpSSG rhabdomyosarcoma 2005 study (1523 aged <15 years and 196 aged 15–21 years) and 258 patients were from the EPSSG MTS 2008 study (197 aged <15 years and 61 aged 15–21 years). Adolescent and young adult patients were more likely than were children to have metastatic tumours (61 [23·7%] of 257 vs 197 [11·5%] of 1720; p<0·0001), unfavourable histological subtypes (119 [46·3%] vs 451 [26·2%]; p<0·0001), tumours larger than 5 cm (177 [68·9%] vs 891 [51·8%]; p<0·0001), and regional lymph node involvement (109 [42·4%] vs 339 [19·7%]; p<0·0001). Adolescent and young adult patients had lower 5-year event-free survival (52·6% [95% CI 46·3–58·6] vs 67·8% [65·5–70·0]; p<0·0001) and lower 5-year overall survival (57·1% [50·4–63·1] vs 77·9% [75·8–79·8]; p<0·0001) than did children. The multivariable analysis confirmed the inferior prognosis of patients aged 15–21 years (hazard ratios 1·48 [95% CI 1·20–1·83; p=0·0002] for poorer event-free survival and 1·73 [1·37–2·19; p<0·0001] for poorer overall survival). Modifications of administered chemotherapy occurred in 13 (15·3%) of 85 adolescents and young adults, and in 161 (21·4%) of 754 children. Grade 3–4 haematological toxicity and infection were observed more frequently in children than in adolescent and young adult patients. Interpretation: This study found better outcomes for adolescent and young adult patients than those reported in epidemiological studies (eg, the EUROCARE-5 study reported 5-year overall survival of 39·6% for patients aged 15–19 years in the 2000–07 study period), suggesting that adolescent and young adult patients, at least up to age 21 years, can be treated with intensive paediatric therapies with no major tolerability issues and should be included in paediatric rhabdomyosarcoma trials. However, the inferior outcomes in adolescent and young adult patients compared with those in children, despite receiving similar therapy, suggest that a tailored and intensive treatment strategy might be warranted for these patients. Funding: Fondazione Città della Speranza.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Quantitative diffusion-weighted MRI response assessment in rhabdomyosarcoma: an international retrospective study on behalf of the European paediatric Soft tissue sarcoma Study Group Imaging Committee

Objective: To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) as a predictive imaging marker after neoadjuvant chemotherapy in patients with rhabdomyosarcoma. Material and methods: We performed a multicenter retrospective study including pediatric, adolescent and young adult patients with rhabdomyosarcoma, Intergroup Rhabdomyosarcoma Study group III/IV, treated according to the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS2005 or MTS2008 studies. DW-MRI was performed according to institutional protocols. We performed two-dimensional single-slice tumor delineation. Areas of necrosis or hemorrhage were delineated to be excluded in the primary analysis. Mean, median and 5th and 95th apparent diffusion coefficient (ADC) were extracted. Results: Of 134 included patients, 82 had measurable tumor at diagnosis and response and DW-MRI scans of adequate quality and were included in the analysis. Technical heterogeneity in scan acquisition protocols and scanners was observed. Mean ADC at diagnosis was 1.1 (95% confidence interval [CI]: 1.1–1.2) (all ADC expressed in * 10−3 mm2/s), versus 1.6 (1.5–1.6) at response assessment. The 5th percentile ADC was 0.8 (0.7–0.9) at diagnosis and 1.1 (1.0–1.2) at response. Absolute change in mean ADC after neoadjuvant chemotherapy was 0.4 (0.3–0.5). Exploratory analyses for association between ADC and clinical parameters showed a significant difference in mean ADC at diagnosis for alveolar versus embryonal histology. Landmark analysis at nine weeks after the date of diagnosis showed no significant association (hazard ratio 1.3 [0.6–3.2]) between the mean ADC change and event-free survival. Conclusion: A significant change in the 5th percentile and the mean ADC after chemotherapy was observed. Strong heterogeneity was identified in DW-MRI acquisition protocols between centers and in individual patients. Graphical Abstract: [Figure not available: see fulltext.].SCOPUS: ar.jinfo:eu-repo/semantics/publishe