[Role of radiotherapy in combined therapy of soft tissue sarcoma in children and adolescents].

Over last decades with modern approach to combined treatment of soft tissue sarcoma in children and adolescents, with effective systemic chemotherapy and adequate local control most frequently with conservative surgery and radiotherapy, or radiotherapy alone, results of treatment from 20% of a three-year overall survival to 75% were improved significantly. Nevertheless, combined treatment involves risk of acute radiation reactions and late side effects, so there is a need for precise radiotherapy planning with optimal schedule of fractionating, adequate radiation volume and optimal tumour dose. The purpose of our study was to evaluate the results of combined treatment of soft tissue sarcoma, role of radiotherapy in local control use of the optimal tumour dose and assessment of acute radiation reactions in an examined group of patients. A retrospective clinical study involved 47 patients treated with radiotherapy at the Institute of Oncology and Radiology of Serbia over the period from 1990 to 1997. The most frequent tumour sites were the head and neck and the extremities. According to the IRS classification most patients were in CS III (21 patients). Forty patients had histological type--Rhabdomyosarcoma (Table 1). All patients were treated with chemotherapy, and local therapy were surgery and radiotherapy or radiotherapy alone. Thirty one patients were operated on. All 47 patients were treated with radiotherapy; in 37 patients as primary treatment and in 10 patients as therapy for local relapse. Radiotherapy was planned according to tumour size, tumour site, age of the patient and type of surgery. Tumour dose from 45 Gy to 60 Gy was given in cases with a residual tumour. Lower tumour doses were used in cases of postoperative microscopic disease, in certain cases of local relapse treatment or when the size of residual tumour and patient's age allowed no delivery of higher tumour doses. Standard fractionating regimen was given to all patients, with daily fractions from 150 cGy to 214 cGy, five times per week. The majority of patients (24) were treated on Linear Accelerator machine with X photons of 10 MeV energy and with X photons of 6 MeV energy (13 patients) (Table 2). Statistical data processing was made by the following methods: Kaplan-Meier for survival rate and Long-rang and Wilcox test for assessment of the statistical significance in survival difference. In our group of patients treated over the period from 1990 to 1997 a three-year overall survival was 59.15%, and disease free survival was 46.68% (Figure 1). There were 21 patients (44.7%) without signs of the disease, 12 patients had a local disease (25.5%), 9 patients had both local and metastatic disease (19.1%) and 5 patients had only metastatic disease (10.50%). In the group of 47 patients who received radiotherapy, 24 patients received a tumour dose from 45 Gy to 60 Gy and 23 patients a tumour dose from 32 Gy to 45 Gy. The group of patients treated without tumour dose more than 45 Gy had a significantly better overall survival rate (p = 0.002) (Figure 2). Although the obtained results are in agreement with data from literature, a critical analysis is necessary. Namely, in addition to the group irradiated with a tumour dose from 32 Gy to 45 Gy, because of the postoperative microscopic disease, certain number of patients was irradiated with a "lower" dose because of an objective impossibility to administer a "higher" dose or this dose was planned for palliative reasons. The tumour dose of 45 Gy was delivered to 6 of 10 patients treated for local relapse. The tumour dose of 45 Gy was also used in four patients in CS IV, in two subjects for local control and in two as a palliative treatment. Seven patients in CS III received a tumour dose of 45 Gy, because the age of children, tumour site and tumour size permitted no higher tumour doses. That is when planning an adequate local therapy one must have in mind the initial tumour size, type of administered systematic chemo