Patients with nonmetastatic embryonal rhabdomyosarcoma arising in the biliary tract should be treated on low‐risk clinical trials

Abstract

In 2000, the Intergroup Rhabdomyosarcoma Study Group (IRSG) moved the biliary tract from an unfavorable to a favorable site in the rhabdomyosarcoma (RMS) staging system 1 after an analysis of patients treated on IRS I-IV documented a high incidence of toxic death but a low rate of death due to recurrent disease in patients with biliary tract RMS. 2 This change moved patients with clinical group III biliary tract RMS from intermediate-risk to low-risk studies. Aye et al. 3 now argue that because the 5-year event-free survival (EFS) for patients with biliary tract RMS on more recent IRSG/COG (Children's Oncology Group) low-risk studies was lower than the target 5-year EFS for low-risk patients with RMS, the biliary tract should revert to an unfavorable site, shifting those with clinical group III tumors back to intermediate-risk studies. Although the EFS on recent low-risk RMS trials was lower than anticipated, a careful examination of the events observed suggests that intensifying systemic therapy by moving these patients to intermediate-risk studies is not the appropriate remedy. The first issue with Aye et al.'s analysis is that two of the events (death due to sepsis/sinusoidal obstruction syndrome and local recurrence that was successfully salvaged) occurred in patients with clinical group I/II embryonal RMS (ERMS). All published IRSG/COG studies have assigned patients with clinical group I/II ERMS to low-risk therapy due to their favorable prognosis 4-9 ; thus, reclassifying the biliary