Thoracic Sarcomas in Children

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Abstract
This study reviews the experience of the Intergroup Rhabdomyosarcoma Studies (IRS) II and III with thoracic sarcomas. Thoracic sarcomas in children present special problems with histologic diagnosis, total resection of tumor, and local control. Previous studies have shown high rates of local and distant relapse. Data from evaluable patients enrolled in IRS II and IRS III were reviewed. Progression-free and overall survival were estimated by the Kaplan-Meier method and statistical differences were calculated by the log-rank test. The multivariate regression analysis of data was performed using the Cox proportional hazards model. A total of 84 patients presented with thoracic sarcomas during IRS II (51 patients) and IRS III (33 patients). Of these, 76 were chest wall tumors, 3 were lung tumors, 4 were pleural tumors, and 1 arose from the heart. The average age at diagnosis was 8.5 years (range, 1 month-20.5 years). Thirty-three patients had alveolar histology, 17 had embryonal histology, and 12 had extraosseous Ewing's sarcoma, with indeterminate, undifferentiated, and pleomorphic histologies in the remaining 22 patients. Thirteen patients presented as group I (localized disease completely resected), 18 as group II (microscopic residual or nodal disease), 31 as group III (gross residual disease or biopsy only), and 22 as group IV (distant metastatic disease). Sixty patients (71%) achieved a complete response. Thirty-nine patients had a local relapse, and 22 had a distant relapse. Thirty-five patients (42%) survived with a mean follow-up of 1.8 years (range 0.7-11.7 years); 49 (58%) have died with an average survival of 1.1 years (range 0.3-11.7 years). Four patients (5%) died of infection or treatment complications. Progression-free survival was not significantly associated with histology, site, clinical group, or IRS study. Overall survival was significantly associated with clinical group, size, and local or distant recurrence, but not with histology or IRS study by univariate analysis. In a multivariate analysis, only clinical group and local and distant recurrence showed statistical significance (p < 0.002, <0.006, and <0.001, respectively). As expected, outcome was better for patients with totally resected or microscopically residual tumor after resection. A higher rate of recurrence in group I versus group II, although not statistically significant, suggests that identification of margin status may be difficult, and these patients may require more intensive efforts for local control. These patients continued to have a high rate of local and distant relapse, and new strategies for preventing these are under development.