Radiotherapy and long-term sequelae in pediatric patients with parameningeal rhabdomyosarcoma : Results of two Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry

BackgroundParameningeal location of rhabdomyosarcoma (PM RMS) is known to be an unfavorable prognostic factor. Scarce data are available on radiotherapy (RT) concepts with regard to outcome.MethodsTreatment and outcome of 395 children with PM RMS registered within two Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry (1995-2021) were evaluated.ResultsPatients were IRS group II (n = 15) and III (n = 380) and received systemic treatment according to the enrolled protocols: I2VA (n = 172), VAIA/CEVAIE (n = 223). Delayed resection was performed in 88/395 (22%) patients, and RT was additionally given in 79/88 (90%) resected patients. RT was the predominant local treatment in 355/395 (90%) patients: hyperfractionated accelerated photon (HART; n = 77), conventionally fractionated photon (n = 91) or proton beam (n = 126), brachytherapy (n = 4), heavy ions (n = 1), not available (n = 56). In the subgroup of RT as only local treatment (n = 278), no intracranial tumor extension and complete remission at end of treatment were significant positive prognostic factors. No significant difference on tumor outcome was seen between different radiotherapy concepts. Long-term toxicity with mostly endocrinological and visual deficiencies was reported in 161/279 (58%) surviving patients with a lower trend after proton beam RT (48%) when compared to HART or conventionally fractionated photon RT (71% and 72%, respectively). Ten-year event-free and overall survival in the overall group were 62% (+/- 5, 95% confidence interval [CI]) and 67% (+/- 5, 95% CI); in the RT-only group 67% (+/- 6, 95% CI) and 71% (+/- 6, 95% CI), respectively.ConclusionCWS data confirm the recent RT concept in PM RMS. Long-term sequelae as endocrinological and visual deficiencies need to be addressed

Significance of fusion status, Oberlin risk factors, local and maintenance treatment in pediatric and adolescent patients with metastatic rhabdomyosarcoma : Data of the European Soft Tissue Sarcoma Registry SoTiSaR

Background: Outcome of primary metastatic rhabdomyosarcoma (RMS) is poor. Certain risk factors as fusion status, Oberlin score, and local treatment of primary tumor are known to influence prognosis. Procedure: Patients with metastatic RMS were treated according to Cooperative Weichteilsarkom Studiengruppe (CWS) guidance with chemotherapy (CHT), radiotherapy (RT) excluding total lung irradiation (TLI), complete resection of the primary tumor, and metastasectomy if possible. Kaplan-Meier estimators and Cox proportional hazard models were used to examine event-free survival (EFS) and overall survival (OS) involving also landmark analyses. Results: In the European Soft Tissue Sarcoma Registry SoTiSaR (2009-2018), 211 patients were analyzed. Many patients had fusion-positive alveolar RMS (n = 83; 39%). Median age was 9.4 years [0.1-19.7 years]. Treatment primarily consisted of CHT with CEVAIE (carboplatin, epirubicine, vincristine, actinomycin-D, ifosfamide, etoposide: 86%, other regimens: 14%), RT (71%), resection of primary tumor (37%), metastasectomy (19%), and lymph node sampling/dissection (21%). Maintenance treatment (MT) (oral trofosfamide, idarubicin, etoposide) was added in 74% of patients. Oberlin factors, fusion status, and MT were predictive for EFS and OS. MT with O-TIE was not improving outcome when adjusting for the immortal time bias. Local treatment of the primary tumor and radical irradiation (except TLI) improved EFS, not OS, when adjusting for the Oberlin score. Patients with fusion-negative alveolar RMS (n = 9) had an excellent outcome with a 5-year EFS and OS of 100%, compared to patients with embryonal RMS (49%/62%), PAX7- (22%/47%) and PAX3/FOXO1-positive ARMS (10/13%), respectively (p < .001). Conclusions: Prognosis of metastatic RMS primarily depends on fusion status and Oberlin score. Fusion status needs to be considered in future trials to optimize treatment outcome. The role of radical irradiation needs further investigation