Localised rhabdomyosarcoma in infants (< 12 months) and young children (12-36 months of age) treated on the EpSSG RMS 2005 study

Slater O, Gains J, Kelsey A, De Corti F, Zanetti I, Coppadoro B, Jorgensen M, Gallego S, Orbach D, Glosli H, Cesen M, Gaze MN, Smeulders N, Ferrari A, Jenney M, Minard-Colin V, Bisogno G, .Merks JHM for the European paediatric Soft tissue sarcoma Study Group Eur J Cancer. 2022 Jan;160:206-214. doi: 10.1016/j.ejca.2021.10.031. Epub 2021 Dec 2.

Background: Infants (<12 months) with rhabdomyosarcoma have historically had poorer outcome than the older age groups. We present outcomes for infants and young children aged 12-36 months with localised rhabdomyosarcoma with a particular emphasis on infants.

Patients and methods: All children less than 36 months of age enrolled on the EpSSG RMS 2005 study for localised disease are included. Treatment comprised chemotherapy, local surgery and/or radiation therapy adapted to risk group and age. Main outcome measures were event free survival (EFS) and overall survival (OS).

Results: Outcome data were available for 485/490 patients aged less than 36 months, 110 were infants. Infants received chemotherapy according to the risk group with no toxic deaths. Radiotherapy was delivered to 33.6% of infants and 63.5% of 12-36 months old, with respectively 41.7% and 22.2% receiving brachytherapy. Radical surgery was performed in 62% of infants and 57.1% of 12-36 months old. Median follow up for patients who are alive (n = 393) was 72.7 months (range 6.9-158.2). Five-year OS for infants was 88.4% (95%CI 80.3-93.2), which is significantly better than the OS in 12-36 months old patients of 78.0% (95%CI 73.2-82.0; p = 0.0204). Five-year EFS for infants was 72.5% (95%CI 62.8-80.0) compared with 66.1% (95%CI 61.0-70.7; p = 0.2663) for 12-36 months old.

Conclusion: Infants treated on RMS 2005 achieved excellent EFS and OS. The EpSSG RMS 2005 chemotherapy regimen, combined with an increase in the application of adequate local therapy, improvements in imaging and supportive care and potentially favourable patients' characteristics may have contributed to these results.

Keywords: EpSSG; Infants; RMS 2005; Rhabdomyosarcoma; Young children.