Rhabdomyosarcoma in the first year of life. Experience of Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood, but is very rare in infants. RMS diagnosed during the first year of life is reported to have poor outcome. The aim of the study was to analyze the results of therapy of RMS in the first year of life treated in federal center in Russian Federation. This study is supported by the Independent Ethics Committee and approved by the Academic Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. All prospectively registered patients with RMS in infants treated during the period 02.2012–05.2018 (75 month) were included. Diagnosis was confirmed by histology. All patients were examined and stratified according to the GPOH Cooperative Weichteilsarkom Study (CWS) Group guidance 2009. 13 prospectively registered patients with RMS in infants treated during the period were included. Median age at initial diagnosis was 6.7 (range 0.23–11.9) months. The tumor was detected prenatally at 32 and 33 weeks of gestation in 2 (15%) patients. The age of these patients was ≤ 1 month in 2 of 13 patients. Tumor size was ≤ 5 cm in 8 (61,5%) of 13 patients. Median volume tumor was 24 (range 0.001–150) ml. The primary site was head and neck (n = 4; 31.5%), pelvis (n = 3; 23%), extremities (n = 3; 23%), genitourinary system (n = 2; 15%), other (n = 1; 7.5%). IRS stage distribution was stage III in 12 (92.5%) patients, stage IV – 1 (7.5%). Regional nodal metastasis (N1) occurred in 1 (7.5%) patient with tumor of the head and neck nonparameningeal. Distant metastasis occurred in 1 (7.5%) patient and the site of spread was subcutaneous fat (blueberry muffin syndrome), pleura, roots of both lungs, pancreas, bone marrow. Histology of these infants was RMA (n = 6; 46%), RME (n = 6; 46%) and spindle-cell RMS (n = 1; 7.5%). The FOXO1-fusion positive status was found in 4/6 patients RMA by fluorescence in situ hybridization (FISH). 11/13 (85%) patients were categorized as high risk, 1/13 (7.5%) as very high risk, 1/13 (7.5%) – treatment for stage IV patients with metastatic disease. All patients (n = 13; 100%) received chemotherapy according to CWS guidance 2009 protocol. All patients were administered at a reduced dose according to body weight. The distribution of treatment regimens was as follows: 11/13 (85%) – IVA, 1/13 (7.5%) – IVADO, 1/13 (7.5%) – CEVAIE. 3/13 patients aged less than 1 month was administered chemotherapy according to VAC. Initial surgery included biopsy in 8/13, surgery – 5/13 (R2 – resection). Local control was provided in 11/13 (85%) patients: only surgery in 7/13 (54%) patients, only radiotherapy in 1/13 (7.5%), radiotherapy and surgery 1/13 (7.5%), only brachytherapy 1/13 (7.5%), brachytherapy and surgery in 1/13 (7.5%). 2/13 patients were not local control: one patient with favorable site (vagina) and one patient with stage IV that showed complete response after chemotherapy in both cases. Radiotherapy including brachytherapy was administered of the all patients at the over 1 year. Radiotherapy was used in 2 of 13 patients (dose range 50.4 Gy and 51.2 Gy), brachytherapy – 36 Gy. At the start of the radiotherapy the age was 21.1 and 13.37 months, brachytherapy – 12,4 and 14,5 months. Second-look surgery was performed in 9/13 (69%) patients: R0 (n = 7), R1 (n = 1), R2 (n = 1). 2/9 patients were performed mutilating surgery: orbital exenteration and cystectomy. Induction therapy was completed in 12 (92.5%) of 13 patients. Median follow-up time was 42.7 (range 3.7–90) months. 8 patients were alive, 5 died. 8/13 patients whom alive were observation: 6/8 patients no relapse/progressive, 2/8 patients – remission after local relapse and progression. 3-year overall survival was 68,4% (95% confidence interval 42,6–94,1. 3-year event-free survival was 46,2% (95% confidence interval 19,1–73,3). Patients aged less than 1 year are particularly problematic. The relatively low event-free survival rate in this age group is associated with the impossibility of carrying out the entire volume of multimodal therapy and required a tailored therapeutic approach.