A review of 331 rhabdomyosarcoma cases in patients treated between 1991 and 2002 in Japan

To prepare for a Japanese nationwide group study of patients with rhabdomyosarcoma (RMS), we examined the characteristics and outcomes of RMS patients treated recently in Japan. We classified 331 RMS patients treated between 1991 and 2002 at 63 institutions according to the Intergroup Rhabdomyosarcoma Study V (IRS-V) risk-group classification. Ten-year survival rates were 86.3% for patients in low-risk subgroup A, 80.7% for low-risk subgroup B, 62.7% for intermediate-risk subgroup A, 61.7% for intermediate-risk subgroup B, and 38.1% for the high-risk group. The outcomes of the patients in the former three groups were 8%, 12%, and 21% worse than the outcomes of the respective patients in the IRS-III and early IRS-IV data. The frequency of the alveolar histological subtype was 21.8%. Chimera genes, which are useful markers for the alveolar subtype, had been examined in only 10% of the patients treated in the period of this investigation. The survival rates of our patients with embryonal and alveolar histological subtypes (65.9% and 63.4%, respectively) were not significantly different. Among the patients in the high-risk group, the 5-year survival of patients who received high-dose chemotherapy (HDC; 58.2%) was significantly better than that of patients who did not receive HDC (18.4%). Patients in the lower-risk groups with embryonal-type tumors had poorer outcomes in this retrospective study. The better outcome of patients in the high-risk group is apparently due to the outstanding results obtained with an HDC regimen in a single institution. These results suggest that there is a need for: (1) a standard therapy, (2) a rapid central pathology review including a chimera gene analysis for the lower-risk group, and (3) evaluation of the efficacy of the high-dose regimen for the high-risk group in Japan.