Prognostic Significance of Tumor Response at the End of Therapy in Group III Rhabdomyosarcoma: A Report From the Children's Oncology Group

Abstract

A B S T R A C T PurposeSome patients with rhabdomyosarcoma (RMS) achieve less than a complete response (CR) despite receiving all planned therapy. We assessed the impact of best response at the completion of all therapy on patient outcome. Patients and MethodsWe studied 419 clinical group III participants who completed all protocol therapy without developing progressive disease for Intergroup Rhabdomyosarcoma Study (IRS) IV. Response (complete resolution [CR], partial response [PR; Ն 50% decrease], or no response [NR; Ͻ 50% decrease and Ͻ 25% increase]) was determined by radiographic measurement and categorized by the best response. ResultsAt the end of therapy, 341 participants (81%) achieved a best response of CR and 78 (19%) had a best response of PR/NR. Five-year failure-free survival was similar for participants achieving CR (80%) and PR/NR (78%). After adjustment for age, nodal status, primary site, and histology, there was no significant indication of lower risk of failure (hazard ratio [HR], 0.77; 95% CI, 0.46 to 1.27; P ϭ .3) nor death (HR, 0.63; 95% CI, 0.36 to 1.09; P ϭ .1) for CR versus PR/NR participants. Seventeen participants with a best response of PR/NR had surgical procedures; eight (50%) of 16 with available pathology reports had residual viable tumor and only three achieved a complete resection. Resection of residual masses was not associated with improved outcome. ConclusionCR status at the end of protocol therapy in clinical group III participants was not associated with a reduction of disease recurrence and death. Aggressive alternative therapy may not be warranted for RMS patients with a residual mass at the end of planned therapy.

Rhabdomyosarcoma of the head and neck in children: Review and update

“…Second look surgeries of residual tumor either during or at the end of therapy have previously been evaluated. Persistence of radiographic masses at the end of therapy is well known, but biologic potential is uncertain, and resection of residual masses at the end of therapy has not been associated with improved outcome [26]. However, second look surgeries may demonstrate whether viable tumor is present, which has decreased failure free survival compared to those without viable tumor [27].…”

What is new in the biology and treatment of pediatric rhabdomyosarcoma?

“…Standard cross-sectional imaging (CT or MRI) performed either early (23) or late in the treatment plan (24) fail to predict disease recurrence. A single institutional review demonstrated that patients who had a negative PET following induction chemotherapy and radiotherapy had a superior local-relapse free survival than patients with a positive PET (94% vs. 75%, 0=0.02) (25) In the future, FDG-PET might replace conventional staging imaging studies, particularly for lymph node disease.…”

Adult Primary Prostate Embryonal Rhabdomyosarcoma: Report of a Case and Revue of Literature

“…This approach was beneficial for confirming the pathologic tumor response, for identifying patients who required second-line chemotherapy. However, the impact of a second-look procedure on survival in group III patients was unclear [21] [30]. In general, modern risk-based multimodality therapeutic protocols including chemotherapy for primary cytoreduction and eradication of both macroscopic and microscopic disease, surgery if feasible, and radiation therapy to control microscopic local residual disease, leads to improved outcomes in children with RMS [23].…”