Prognostic Factors After Relapse in Nonmetastatic Rhabdomyosarcoma: A Nomogram to Better Define Patients Who Can Be Salvaged With Further Therapy

Abstract

Purpose Previous studies suggest poor outcome in children with relapsed rhabdomyosarcoma (RMS). A better understanding is needed of which patients can be salvaged after first relapse. Patients and Methods The analysis included children with nonmetastatic RMS and embryonal sarcoma enrolled onto the International Society of Paediatric Oncology (SIOP) Malignant Mesenchymal Tumor (MMT) 84, 89, and 95 studies who relapsed after achieving complete local control with primary therapy. All patients included in the analysis had follow-up for ≥ 3.0 years after the last event. The clinical features, initial treatment characteristics, and features of the relapse were correlated with survival in univariate and multivariate analyses. Results In all, 474 eligible patients were identified for the study. At ≥ 3.0 years from the last event, 176 (37%) were alive (“cured”). In a full-model multivariate analysis, the factors identified at first relapse that most strongly associated with poor outcome were metastatic relapse (odds ratio [OR], 4.19; 95% CI, 2.0 to 8.5), prior radiotherapy treatment (OR, 3.64; 95% CI, 2.1 to 6.4), initial tumor size > 5 cm (OR, 2.53; 95% CI, 1.5 to 4.1), and time of relapse < 18 months from diagnosis (OR, 2.20; 95% CI, 1.3 to 3.6). Unfavorable primary disease site, nodal involvement at diagnosis, alveolar histology, and previous three- or six-drug chemotherapy were also independently associated with poor outcome. To estimate chance of cure for individual patients, a nomogram was developed, which allowed for weighting of these significant factors. Conclusion Some children with relapsed RMS remain curable. It is now possible to estimate the chance of salvage for individual children to direct therapy appropriately toward cure, use of experimental therapies, and/or palliation.