Salvage Therapy Efficacy is Modified by Risk Group at Diagnosis in Patients With Relapsed Rhabdomyosarcoma.

Area of Science:

• Pediatric Oncology
• Cancer Chemotherapy
• Rhabdomyosarcoma Research

Background:

• Relapsed rhabdomyosarcoma (RMS) presents significant treatment challenges with poor overall survival (OS).
• Current salvage regimens for relapsed RMS vary, necessitating comparative studies for efficacy.
• Investigating high-dose alkylator combinations as a potential therapeutic strategy is crucial.

Purpose of the Study:

• To compare overall survival (OS) in patients with relapsed rhabdomyosarcoma (RMS) based on the use of high-dose alkylator chemotherapy.
• To determine if high-dose alkylator regimens are associated with improved survival outcomes in relapsed RMS.

Main Methods:

• An observational study included 110 patients with relapsed RMS from five institutions.
• Patients were categorized into two groups: those receiving high-dose alkylator regimens (Group A) and those not (Group B).
• Kaplan-Meier and Cox proportional hazards analyses were used to compare OS, adjusting for risk group and institution.

Main Results:

• Patients receiving high-dose alkylator regimens (Group A) demonstrated significantly longer OS compared to Group B (4-year OS 41% vs. 14%, p=0.002).
• The association between high-dose alkylators and improved OS was abrogated after adjusting for risk group at diagnosis (HR 1.4, p=0.16).
• Stratified analyses indicated a potential benefit of high-dose alkylators in low-risk patients (stratified HR 4.4, p=0.06), with no significant effect in intermediate or high-risk groups.

Conclusions:

• Low-risk relapsed rhabdomyosarcoma patients may benefit from high-dose alkylator chemotherapy.
• High-risk relapsed RMS patients face dismal outcomes irrespective of salvage treatment selection.
• The benefit of high-dose alkylator therapy for intermediate-risk patients remains inconclusive.