2001 CTOS Annual Meeting Posters— Radiation Oncology

INDICATIONS FOR RADIOTHERAPY AFTER NEAR COMPLETE RESECTION (MICROSCOPIC RESIDUAL DIESEASE, IRS GROUP II) IN RHABDOMYOSARCOMA: A REPORT FROM THE GERMAN SOFT TISSUE SARCOMA STUDY GROUP CWS
Ewa B Koscielniak¹,  Robert Knietig¹,  Bernhard F Schmidt²,  Denise Kunz¹,  Adrian Mattke¹,  Joern Treuner^1
1Dept.of Pediatric Hematology/Oncology, Olga Hospital,  ²Dept.of Radiotherapy, Katharinen Hospital

METHODS: One hundred thirteen patients with near complete resected localised RMS (IRS Group II) were further treated with chemotherapy ( vincristine, cyclophosphamide or ifosfamide, dactinomycin ± doxorubicin ± VP16) on German Soft Tisse Sarcoma Studies CWS-81 to CWS-96 between 1981-1997. Sixty two patients (54%) also received radiotherapy (RTX). The RTX was recommended for patients with microscopic disease after second look surgery (CWS-81), for patients with extremity and paramenigeal primary tumors and those with bone erosion at presentation (CWS-81 to CWS-91), for patients with alveolar RMS (CWS-91) and for all Group II patients in the CWS-96. In the CWS-81 Study doses between 40-50 Gy (1x 1.8 Gy/day) were administered. Since 1986 the CWS-Group recommend an accelerated hyperfractionated RTX (2 x 1,6 Gy daily) with doses between 32-54 Gy.

RESULTS: Fourteen irradiated (22%) and eighteen (35%) non-irradiated patients relapsed (p=0.1). 78% (25/32) of failure sites were local, 6 % were regional and 15% were distant. The proportion of patients who were irradiated differed slightly between the Studies (43-77%). 61% of patients younger than 3yrs of age were irradiated in contrast to 78% of patients older than 3yrs. The 5 yrs event-free survival (EFS) and 5 yrs overall survival (S) were 80±9% and 85± 8% (CWS-81), 71±7% and 89±5% (CWS-86),73±8% and 93±5% (CWS-91) respectively. The median irradiation dose was 40 Gy (CWS-81), 32Gy (CWS-86), 36,5Gy (CWS-91) and 44Gy (CWS-96). In the multivariate analysis no differences in EFS were observed by tumor size, site, age, alveolar histology or by whether or not the patient received RTX. However, the alveolar histology was shown to be predictive of overall survival (p=0.01).

CONCLUSION: Patients with group II RMS have a very good prognosis when treated with adjuvant multiagent chemotherapy with or without irradiation. RTX was not found to benefit significantly the EFS and S of patients with embryonal RMS. However, the addition of RTX was associated with improved survival in patients with alveolar RMS.