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To investigate the survival outcomes, the treatment toxicities, and the recurrence pattern of nineteen patients with retroperitoneal sarcoma treated with radiotherapy.

The inclusion criteria for this retrospective study were previously untreated retroperitoneal sarcoma who had received radiotherapy. From March 2016 to October 2020, the chart records and images of 19 eligible patients were reviewed. There were nine males and ten females, and their ages ranged from 34 to 80 years (median 53). Sixteen patients (84.2%) had a liposarcoma, and three patients (15.8%) had a leiomyosarcoma. At diagnosis, four patients (19.1%) had a stage I-II disease, fourteen patients (78.9%) had a stage III disease, and only one patient had a stage IV disease. Eighteen patients (94.7%) received operation, and sixteen of them had a positive or close (< 1mm) surgical margin. Sixteen patients (84.1%) received adjuvant radiotherapy (median dose 5400cGy, ranging 5000 to 6000cGy), one patient (5.3%) received neoadjuvant radiotherapy (5000cGy), one patient received definitive chemoradiotherapy (7000cGy), and one patient received palliative radiotherapy (3000cGy) to bone metastasis.

The medial follow-up was 34 months, and the two-year overall survival rate was 78.9%. Acute toxicities of radiotherapy included gastrointestinal toxicities (grade 1-2: 8 patients), nausea (grade 1-2: 4 patients, grade 3-4: 3 patients), vomiting (grade 1-2: 3 patients, grade 3-4: 2 patients), neutropenia (grade 1-2: 2 patients, grade 3-4: 1 patients), and fatigue (grade 1-2: 5 patients). In patients without metastatic disease at diagnosis, two-year overall survival rate was 83.3%, and two-year disease-free survival rate was 64.6%. There were 8 recurrences (2 local alone, 2 distant metastasis alone, 1 local plus regional, 2 local plus distant metastasis, and 1 local plus regional plus distant metastasis), and 5 deaths. Recurrent metastatic locations included lung (n=1), liver (n=1), bone (n=2), peritoneum (n=1), distant lymph nodes (n=1), and soft tissue of thigh (n=1). One patient with metastatic disease at diagnosis expired due to disease progression with 8 months survival.

Radiotherapy in retroperitoneal sarcoma provided an acceptable two-year survival rate with tolerable toxicities, but recurrence rate was still high. About 62.5% of recurrent events consisted of local recurrence, so close follow up of primary tumor area is necessary.