Proton-beam, intensity-modulated, and/or intraoperative electron radiation therapy combined with aggressive anterior surgical resection for retroperitoneal sarcomas

Abstract

Background: We sought to reduce local recurrence for retroperitoneal sarcomas by using a coordinated strategy of advanced radiation techniques and aggressive en-bloc surgical resection.

Methods: Proton-beam radiation therapy (PBRT) and/or intensity-modulated radiation therapy (IMRT) were delivered to improve tumor target coverage and spare selected adjacent organs. Surgical resection of tumor and adjacent organs was performed to obtain a disease-free anterior margin. Intraoperative electron radiation therapy (IOERT) was delivered to any close posterior margin.

Results: Twenty patients had primary tumors and eight had recurrent tumors. Tumors were large (median size 9.75 cm), primarily liposarcomas and leiomyosarcomas (71%), and were mostly of intermediate or high grade (81%). PBRT and/or IMRT were delivered to all patients, preferably preoperatively (75%), to a median dose of 50 Gy. Surgical resection included up to five adjacent organs, most commonly the colon (n = 7) and kidney (n = 7). Margins were positive for disease, usually posteriorly, in 15 patients (54%). IOERT was delivered to the posterior margin in 12 patients (43%) to a median dose of 11 Gy. Surgical complications occurred in eight patients (28.6%), and radiation-related complications occurred in four patients (14%). After a median follow-up of 33 months, only two patients (10%) with primary disease experienced local recurrence, while three patients (37.5%) with recurrent disease experienced local recurrence.

Conclusions: Aggressive resection of retroperitoneal sarcomas can achieve a disease-negative anterior margin. PBRT and/or IMRT with IOERT may possibly deliver sufficient radiation dose to the posterior margin to control microscopic residual disease. This strategy may minimize radiation-related morbidity and reduce local recurrence, especially in patients with primary disease.

FIG. 1

a Axial and coronal images of right retroperitoneal well-differentiated and dedifferentiated liposarcoma along with isodose lines that indicate the percentage of the proton-beam radiation prescription. b Follow-up computed tomographic scan 4 years after surgery and radiation

FIG. 2

a Axial images of abdominal computed tomographic (CT) scan demonstrating right malignant fibrous histiocytoma retroperitoneal sarcomas abutting psoas muscle (red arrows). b Proton-beam radiotherapy planning CT scan demonstrating omental flap (yellow arrows) and isodose lines

FIG. 3

a Axial images of abdominal magnetic resonance imaging demonstrating myxoid liposarcoma (outlined in yellow arrows) encasing left gastric vessels (red arrowhead) and celiac axis (yellow arrowhead). b Proton-beam radiotherapy planning computed tomographic scan demonstrating isodose lines. c Dose volume graphs comparing IMRT versus 3D conformal protons (3DCPT) for liver, small bowel, stomach, kidney, colon, and spinal cord

FIG. 4

a Axial images of abdominal computed tomographic (CT) scan at the level of hepatic veins and the level of renal veins demonstrating retrohepatic inferior vena cava (IVC) leiomyosarcoma. b Proton-beam radiotherapy planning CT demonstrating isodose lines. c Intraoperative photographs demonstrating IVC with tumor (yellow arrows) and IVC replacement with ringed polytetrafluoroethylene graft with IVC cuff around hepatic veins sewn into graft (white arrows)

FIG. 5

Local recurrence-free survival stratified by primary versus recurrent tumor a or by retroperitoneum versus pelvis site b. Distant recurrence-free survival for all patients c or stratified by tumor location d. e Disease-specific survival for all patients

FIG. 6

Depth-dose distributions for a single field of 15 MV photons and a spread-out Bragg peak (SOBP) 23 cm in range and 12 cm in modulation. Modified from Suit and Chu