Local staging and treatment in extremity rhabdomyosarcoma. A report from the EpSSG-RMS2005 study.

Unlabelled: Rhabdomyosarcoma of the extremities present with two main challenges: correct evaluation of initial regional nodal involvement and define adequate local treatment.

Methods: Pediatric patients with localized rhabdomyosarcoma of the extremity included in the EpSSG-RMS2005 study between 2005 and 2014 were evaluated for staging, treatment, and survival. The outcome was compared to the preceding European SIOP-MMT studies.

Results: Of the 162 patients included, histology was unfavorable in 113 (70%), 124 (77%) were younger than 10 years, 128 (79%) were IRS III, and 47 (29%) were node-positive. A regional node biopsy was performed in 97 patients (60%) and modified the lymph node stage in 15/97 (16%). Primary and delayed surgery was performed in 155 (96%) and radiotherapy delivered in 118 (73%) patients. Relapse occurred in 61 cases (38%), local in 14 (23%), regional in 13 (21%), distant in 22 (36%), and combined relapse in 12 (20%) with five progressive diseases (8%) and four secondary tumors (7%). Five-year event free (EFS) and overall survival (OS) were 58.4% (95%CI, 50.3-65.7) and 71.7% (63.6-78.4), respectively. In the previous studies MMT89 and MMT95, tumor surgery was performed in 32/53 (60%) and 74/82(90%), respectively, and radiotherapy delivered in 13/53 (25%) and 26/82 (30%), respectively. Five-year EFS and OS were 35.6%, and 50.3% in MMT89 and 54.3% and 68.2% in the MMT95 study.

Conclusions: Even if the lymph node staging was not always complete according to the RMS2005 protocol, node sampling changed lymph node status in a significant number of patients. Despite the higher rate of patients treated with locoregional radiotherapy, survival in RMS2005 did not improve compared to the previous European SIOP-MMT95 study.