REDUCING CHEMORADIOTHERAPY SAFE FOR SOMERABDOMYOSARCOMAS

NEW YORK (Reuters Health) Mar 03 - Reducing the use of radiotherapy and eliminating cyclophosphamide has been found safe and effective in some patients with newly diagnosed, low-risk embryonal rhabdomyosarcoma (ERMS).
The findings are the latest from The Intergroup Rhabdomyosarcoma Study Group (IRSG), and were published online February 28th in the Journal of Clinical Oncology.
In previous studies the same researchers who conducted this study found that patients with localized, grossly resected, or gross residual (orbital only) ERMS had 5-year failure-free survival rates of 83% and overall survival rates of 95%. That was using specially designed protocols for low-risk patients established by the IRSG. Those regimens included vincristine and dactinomycin with or without cyclophosphamide and radiation therapy.
The aim of the present study was to see if it was feasible, in a similar cohort of patients, to decrease toxicity by reducing radiotherapy doses and eliminating cyclophosphamide in patients at lowest risk.
The researchers stratified 342 patients by risk. The lower risk group (n=264) included embryonal ectomesenchymoma or ERMS patients categorized as stage 1 group I/IIA, stage 1 group III orbit, or stage 2 group I.
The higher risk group (n=78) included patients with stage 1 group IIB/C, stage I group III nonorbit, stage 2 group II, or stage 3 group I/II ERMS.
The researchers' specific objectives were three-fold:
1. To estimate failure-free survival rates of patients in subgroup A after vincristine and dactinomycin chemotherapy for 45 weeks, plus radiation therapy for patients with residual tumor;
2. To estimate failure-free survival rates of patients in subgroup B after vincristine and dactinomycin plus cyclophosphamide for 45 weeks, plus radiation therapy for patients with residual tumors;
3. And to ascertain local control and failure-free survival rates in three selected groups of patients given radiation therapy doses 5-10 Gy lower than in previous studies: 36 Gy for stage 1 group IIA, 45 Gy for stage 1 group III N0 orbit, and 36 Gy for stages 2/3 group IIA patients.
Estimated 5-year failure-free survival rates were 89% for patients in the lower risk group, and 85% for the higher risk group, after median follow-up of 5.1 years.
For patients with stage 1 group IIA tumors (n=62), estimated 5-year failure-free survival rates were 81%. For patients with group III orbit tumors (n=77), estimated 5-year failure-free survival was 86%.
The study group says 5-year failure-free survival and overall survival were similar to that observed in IRS-III patients, including those that were treated with reduced doses of radiation. Failure-free survival and overall survival were lower, however, than comparable IRS-IV patients that received vincristine and dactinomycin plus cyclophosphamide. Five-year failure-free survival rates were similar among the lower risk and higher risk patients.
Rhabdomyosarcoma is the most common type of soft-tissue sarcoma in children. The annual incidence of the disease in the U.S. is 4.5 cases per 1 million children younger than 14 years. About 250 new cases are diagnosed each year, nearly two thirds being embryonal rhabdomyosarcomas.