Feasibility of Preoperative Dose-Painting Intensity Modulated Radiation Therapy (IMRT) for Borderline-Resectable Primary Retroperitoneal Sarcoma.

Purpose: The role of radiation therapy (RT) in resectable retroperitoneal sarcoma (RPS) remains controversial; however, preoperative RT may play an important role in borderline-resectable (at risk of R2 resection) disease. We evaluated the outcome of such patients treated with preoperative dose-painting IMRT followed by planned resection.

Methods: Between January 2001 and December 2017, 30 patients with borderline-resectable primary nonmetastatic RPS (after multidisciplinary review) received preoperative dose-painting IMRT in this retrospective cohort study.

Results: Median follow-up for all patients was 32 months. Median dose to the whole tumor/high-risk margin was 50.4 Gy/60.2 Gy. Sixteen patients were female, 24 were >50 years. Median tumor size was 9.2 cm. After RT, 6 did not have surgery. Of the 24 who were explored, 20 underwent complete gross resection. During RT, 7 of 30 patients developed acute grade 2+ toxicities: 5 fatigue, 1 nausea and vomiting, and 1 cystitis. RT was completed in 29 of 30 patients. Postoperatively, 12 of 20 patients developed grade 2+ complications: 2 gastropathy, 5 intraabdominal collections requiring drainage, 1 retroperitoneal bleed, and 3 delayed wound healing. Late grade 2+ toxicity was observed in 3 of 20 patients: 1 lymphedema with recurrent cellulitis, 1 chronic diarrhea, 1 gastrointestinal bleeding from anastomosis requiring transfusions, and 2 renal insufficiency. In those who underwent complete gross resection (n = 20, median follow-up 47 months), the 5-year local control was 57%, and overall survival was 46%.

Discussion: Preoperative dose-painting IMRT given to borderline-resectable RPS rendered 67% of patients resectable, provided a 5-year local control rate of 57%, which is similar to those with resectable disease, and had an acceptable morbidity profile.