Second-line therapy in young patients with relapsed or refractory orbital rhabdomyosarcoma

Objective: Localized orbital rhabdomyosarcoma (oRMS) has an overall favourable prognosis with more than 90% of survival. Little is known about the best strategy in recurrent/refractory (R/R) cases. The purpose is to examine the characteristics of patients with R/R-oRMS, focusing on local therapy.

Methods: This is bicentric retrospective study. Analysis is of young patients (<30 years) with R/R-oRMS who were treated from 1989 to 2018 at the Institut Curie and Gustave Roussy Cancer Campus, France.

Results: Twenty-seven out of 162 patients (17%) with oRMS presented with R/R disease. 6 of these patients had alveolar RMS (22%), 3 of whom had initial parameningeal extension (11%). During first-line treatment, 18 patients (67%) had orbital radiotherapy. Median age at R/R was 10 years (ranges: 4-28) after a delay of 19 months from diagnosis (ranges: 3-40). Tumoral events were local relapses (22 cases), local progression (3 cases) or regional relapses (2 cases). Second-line treatments included chemotherapy (27 cases), radiotherapy (16 cases), surgery (exenteration; 8 cases) and metastasis/ nodal removal (3 cases). After a median follow-up of 99 months (range: 10-306), 4 patients died and 23 are in complete remission (CR) without treatment. One patient had subsequent relapse treated with exenteration and brachytherapy until a new tumour remission. Five-year event-free and overall survivals after first tumour event are, respectively, 84.4% (95% confidence interval: 71.5%-98.8%) and 85.8% (95% confidence interval: 72.1%-100.0%) CONCLUSION: R/R-oRMS is a rare situation. Second-line therapy is efficient in this location, sometime at the cost of lifesaving mutilating surgery. Second-line local therapy needs therefore to consider local radiotherapy if possible or complete wide surgery.