Whole abdominopelvic radiotherapy for desmoplastic small round-cell tumor.

PURPOSE: Desmoplastic small round-cell tumor (DSRCT) is a rare, recently described intraperitoneal malignancy occurring predominantly in adolescent boys. Our objective was to evaluate the feasibility and outcome of whole abdominopelvic irradiation (WAPI) as part of a combined modality protocol for patients with DSRCT. METHODS AND MATERIALS: The records of all 21 patients treated with WAPI for DSRCT at our institution from 1992 to 2001 were retrospectively reviewed. Patients were treated on an institutional protocol with 7 cycles of an alkylator-based chemotherapy. After maximal surgical debulking, patients were treated with external beam radiotherapy to the whole abdomen and pelvis to a dose of 30 Gy.
RESULTS: All 21 patients completed the prescribed treatment. The median follow-up was 28 months. The overall survival and relapse-free survival rate at 3 years was 48% and 19%, respectively. The median survival was 32 months, and the median time to relapse was 19 months. Most relapses were intraperitoneal and/or hepatic. Acute toxicities included Radiation Therapy Oncology Group Grade 2 upper and lower gastrointestinal toxicity in 81% and 71% of patients, respectively. All patients experienced acute hematologic toxicity, with Grade 4 thrombocytopenia, leukopenia, and anemia in 76%, 29%, and 33%, respectively. The major long-term toxicity was small bowel obstruction, which occurred in 7 patients (33%) after surgery and WAPI.
CONCLUSION: DSRCT is a rare and highly lethal disease, requiring aggressive multimodality therapy. WAPI is feasible in conjunction with intensive chemotherapy and surgery. Hematologic and gastrointestinal toxicities are expected but manageable with diligent supportive care. The long-term efficacy of this therapy remains disappointing, thus novel approaches are being investigated.