Comparison of the Rates of Response to Ifosfamide and Cyclophosphamide in Primary Unresectable Rhabdomyosarcomas

In the 1981 cooperative soft-tissue sarcoma (CWS-81) study, a clear correlation between the degree of response to initial chemotherapy comprising vincristine, actinomycin D, cyclophosphamide, and Adriamycin (VACA) and the survival of patients with rhabdomyosarcoma was found. In the subsequent CWS-86 study, cyclophosphamide was replaced by ifosfamide (VAIA) in the expectation that the combination VAIA might be more effective than VACA. In both studies, the initial cytostatic response for primary unresectable tumors was evaluated after the first cycle of chemotherapy at weeks 7-9. The reduction in tumor volume was measured by computerized axial tomographic (CAT) scan or sonography, and the patients were categorized as complete responders, patients with a tumor regression of greater than 2/3 albeit incomplete, patients with a tumor regression of less than 2/3 but greater than 1/3, and nonresponders, who underwent either a tumor regression of less than 1/3 or tumor progression. We compared the response rate obtained with VACA chemotherapy and that resulting from VAIA chemotherapy. The preliminary data from this comparison show a tendency for a higher rate of good responders (complete and less than 2/3 tumor regression) to be induced by VAIA therapy (71%) than that obtained using the VACA combination (55%). From the response-prognosis relationship, we confidently expect that the final outcome for patients in the present study will be better than that in the previous study.