Results of alternating chemotherapy and hyperfractionated radiation therapy in childhood rhabdomyosarcoma.

Abstract

A regimen of multi-drug chemotherapy alternating with split course hyperfractionated radiation therapy (HFRT) was adopted for the treatment of patients with rhabdomyosarcoma (RMS). The purpose of this treatment regimen was to allow for the timely delivery of radiation and chemotherapy, reduce treatment-related toxicity, and improve compliance. Forty-four patients with stages II-IV RMS were treated with HFRT and received 5,400 cGy. The treatment was administered in two courses (3,000 and 2,400 cGy) and separated by a 4-week interval. HFRT consisted of 150 cGy delivered twice a day, 5 days a week with an interfraction interval of 4-6 hours. A limited comparison was made between the HFRT patients and 42 historical patients with comparable clinical characteristics who were treated with similar chemotherapy and conventionally fractionated radiation therapy (CFRT) (median 4,800 cGy, range 4,000-5,680 cGy). HFRT patients completed radiation therapy in 59.1 +/- 9.4 days (mean +/- SD) and CFRT patients completed treatment in 56.6 +/- 10.5 days compared to an expected 52 and 40 days, respectively. With a median follow-up of 55 months for the HFRT patients and 104 months for the CFRT patients, no differences in local control or survival were noted. Nine of 44 (21%) HFRT and 8/42 (19%) CFRT patients experienced local failure. The median time to local failure was 15 months for patients in the HFRT group and 11 months for patients in the CFRT group. The results of the HFRT regimen were acceptable in terms of toxicity and compliance. No improvement in local control was obtained by alternating radiation and chemotherapy. The lack of difference between patients treated with HFRT and CFRT may be related to the lengthened treatment time of the split course regimen, the small difference in total dose, and tumor repopulation.