IS THERE A SAFE THERAPEUTIC WINDOW FOR DELIVERY OF CHEMOTHERAPY PRIORTO INITIATION OF SURGERY AND OR RADIATION-THERAPY FOR TREATMENT OF THE PRIMARY TUMOR IN CHILDREN WITH RHABDOMYOSARCOMA/

To avoid the delayed consequences of treatment with radiotherapy, an e ffort was made to determine if patients with rhabdomyosarcoma could be cured with chemotherapy as the sole form of treatment. Alternatively, if radiotherapy and/or surgery were required to reduce the severity a nd incidence of delayed sequelae, an effort was made to determine if t here was an optimum safe period for delaying implementation of these d efinitive forms of treatment. In patients where primary (immediate) de finitive non-mutilating surgical extirpation of tumor was not feasible , exclusive treatment with chemotherapy was implemented. If considered necessary or appropriate, delayed surgery and/or radiation therapy we re employed in 3 circumstances: (i) to consolidate a partial response; (ii) failure to respond; (iii) recurrent disease. The outcome of the delays prior to the implementation of definitive therapy was analyzed as a function of local and systemic recurrence and cure. Fifty-two pat ients were evaluated. Seven underwent primary non-mutilating surgical extirpation of localized tumor followed by adjuvant chemotherapy. The remaining 45 were treated with primary chemotherapy and 44 responded. Actuarial survival curves of the delay in initiating definitive therap y in the 52 patients revealed that the optimum delay to attain the bes t survival was 5 months. In circumstances where definitive therapy was not electively introduced, recurrent disease during remission appeare d between 7 and 14 months in 7 patients on continued treatment, and in one patient at 30 months, 8 months after discontinuation of chemother apy. Based upon the 5-month delay an analysis of survival was performe d: Definitive therapy was introduced in 14 patients within 5 months an d 7 were cured. In the remaining 31 patients, definitive therapy was i ntroduced between 5 and 30 months and 15 were cured. The five month de lay is supported empirically by tumor doubling times. No patient was c ured exclusively with chemotherapy.