Wiener, Eugene S.

PURPOSE: To identify which patients with rhabdomyosarcoma and microscopic residual disease (group II) are likely to not respond to therapy. PATIENTS AND METHODS: Six hundred ninety-five patients with group II tumors received chemotherapy and 90% received radiation therapy on Intergroup Rhabdomyosarcoma Study (IRS)-I to IRS-IV (1972 to 1997). Tumors were subgrouped depending on the presence of microscopic residual disease only (subgroup IIa), resected positive regional lymph nodes, (subgroup IIb), or microscopic residual disease and resected positive regional lymph nodes (subgroup IIc). RESULTS: Overall, the 5-year failure-free survival rate (FFSR) was 73%, and patients with embryonal rhabdomyosarcoma treated on IRS-IV fared especially well (5-year FFSR, 93%; n = 90). Five-year FFSRs differed significantly by subgroup (IIa, 75% and n = 506; IIb, 74% and n = 101; IIc, 58% and n = 88; P = .0037) and treatment (IRS-I, 68%; IRS-II, 67%; IRS-III, 75%; IRS-IV, 87%; P < .001). Multivariate analysis revealed positive associations between primary site (favorable), histology (embryonal), subgroup IIa or IIb, treatment (IRS-III/IV), and better FFSRs. Patterns of treatment failure revealed local failure to be 8%, regional failure, 4%, and distant failure, 14%. The relapse pattern noted over the course of IRS-I to IRS-IV shows a decrease in the systemic relapse rates, particularly for patients with embryonal histology, suggesting that improvement in FFSRs is primarily a result of improved chemotherapy. CONCLUSION: Group II rhabdomyosarcoma has an excellent prognosis with contemporary therapy as used in IRS-III/IV, and those less likely to respond can be identified using prognostic factors: histology, subgroup, and primary site. Patients with embryonal rhabdomyosarcoma are generally cured, although patients with alveolar rhabdomyosarcoma or undifferentiated sarcoma, particularly subgroup IIc at unfavorable sites, continue to need better therapy.

PURPOSE: To evaluate the outcome of patients with rhabdomyosarcoma (RMS) treated with complete surgical resection and multiagent chemotherapy, with or without local radiotherapy (RT). PATIENTS AND METHODS: Four hundred thirty-nine patients with completely resected (ie, group I) RMS were further treated with chemotherapy (vincristine and actinomycin D ± cyclophosphamide, doxorubicin, and cisplatin) on Intergroup Rhabdomyosarcoma Studies (IRS) I to III between 1972 and 1991. Eighty-three patients (19%) also received local RT as a component of initial treatment. RESULTS: Eighty-six patients relapsed (10-year failure-free survival [FFS] 79%, overall survival 89%). Six percent of failure sites were local, 6% were regional, and 7% were distant. Poor prognostic factors were tumor size greater than 5 cm, alveolar or undifferentiated histology, primary tumor sites other than genitourinary, and treatment on IRS-I or II. For patients with embryonal RMS who were treated with RT, there was a trend for improved FFS but no difference in overall survival. On IRS-I and II, patients with alveolar or undifferentiated sarcoma who received RT compared with those who did not receive RT had greater 10-year FFS rates (73% v 44%, respectively; P = .03) and overall survival rates (82% v 52%, respectively; (P = .02). Such patients who received RT on IRS III also benefited more than those who did not receive RT (10-year FFS, 95% v 69%; P = .01; overall survival, 95% v 86%; P = .23). CONCLUSION: Patients with group I embryonal RMS have an excellent prognosis when treated with adjuvant multiagent chemotherapy without RT. Patients with alveolar RMS or undifferentiated sarcoma fare worse; however, FFS and overall survival are substantially improved when RT is added to multiagent chemotherapy (IRS-I and II). The best outcome occurred in IRS-III, when RT was used in conjunction with intensified chemotherapy.

Ectomesenchymomas (EM) are rare malignant neoplasms usually consisting of rhabdomyosarcoma (RMS) with a neural component. Only 21 cases have been previously reported. Here we extend the clinicopathologic spectrum of EM by describing our findings in 15 cases. Only 5 patients were infants; 10 were ≤3 years old and 5 were ≥6 years old. No male predilection was observed; 7 were female. The originating institutional diagnoses were; RMS (12), undifferentiated sarcoma (1), or EM (2), suggesting underdiagnosis of this entity. The primary tumor sites included external genital (5), pelvis/abdomen (6), head and neck (3), and extremity (1). The size of the primary neoplasm was usually ≥5 cm at diagnosis but dissemination only occurred in a minority. Local infiltration was not uncommon. These neoplasms were typically multilobate, thinly encapsulated, hemorrhagic, and necrotic. Light microscopic features were highly variable, but embryonal RMS with scattered or clustered ganglion cells, often in lacunae, was characteristic. In some cases, primitive neuroblastic or neuroectodermal areas were found and/or a component of alveolar RMS was seen. Focal anaplasia was occasionally observed. Mitotic activity appears higher than previously appreciated and some necrosis was invariably present. Electron microscopy was performed in 11 cases, which confirmed skeletal muscle ± neural differentiation. Cytogenetic studies performed in five cases revealed no specific abnormality. Monoclonal neuron-specific enolase was the best marker of ganglion cells and primitive neural elements. MIC-2 (CD99) membrane expression was not definitively present in any of the six cases examined. A number of the above parameters appear to be of some prognostic significance, but overall, these neoplasms appear to have a similar outcome as would be predicted for their RMS element alone (exclusive of any neural component), with respect to the RMS subtype, age of the patient, and anatomic location of the neoplasm.