Preliminary results of alternating combination chemotherapy (CT) and hyperfractionated radiotherapy (HART) in advanced rhabdomyosarcoma (RMS).

In an attempt to reduce treatment (Rx) related acute toxicity and improve protocol compliance without compromising local control nor overall survival, a Phase II single arm pilot employing alternating intensive multiagent CT and radiotherapy (RT) in children with gross residual or metastatic RMS was begun at Memorial Sloan-Kettering Cancer Center (MSKCC) in 1984. Hyperfractionated radiotherapy (HART) was adopted to allow for timely delivery of both the RT and CT. From July, 1984 through July, 1986 12 patients (pts), aged 2 to 23 yr (median 10 yr) were enrolled on study. CT treatment was delivered over approximately 14 months and included 2 induction and 5 maintenance cycles. The induction CT consisted of two repetitive cycles of Vincristine, Dactinomycin, Cyclophosphamide, Adriamycin, Bleomycin, and Methotrexate; the maintenance CT included the same agents as reduced drug doses. The HART was delivered to the primary site during cycle I of induction at fractions of 150 cGy BID to a total dose of 5400 cGy in 2 courses of 3000 cGy and 2400 cGy, respectively. One hundred percent of patients completed the recommended dose of HART; 0% required unplanned interruptions of HART due to treatment toxicity. With a median follow-up (f/u) from diagnosis of surviving patients of 25 months (range 20-30), the local control rate is 83% (10/12 pts) and the overall survival, 58% (7/12 pts). The median time (MT) to any failure, local or metastatic, is 9 months (mo); and to death, 14 mo. Comparison of results with 12 historical controls with concomitant split-course standard fractionation RT (180-200 cGy/per fraction) and T6 CT during a MSKCC trial from 1975-1984, matched by site and stage of primary, revealed that 9 pts (75%) completed the recommended dose of RT, and 7 pts (58%) required interruptions of RT. With a median f/u of 78 mo (range 34-109), the local control rate was 75% (9/12 pts) and the overall survival, 42% (5/12 pts). The MT to any failure was 14 mo; and to death, 18 mo. These results indicate that the mode of alternating CT and HART (HART T6) as employed in this pilot study is well tolerated. It appears to offer a significant improvement in protocol compliance over previous protocols using concomitant CT and RT without any apparent compromise in local primary control or survival rates with a median f/u suggestive of adequate elapsed time for the appearance of most relapses and deaths in advanced RMS.