Full-dose adjuvant postoperative radiation therapy for retroperitoneal sarcomas.

Objectives: To categorize sites of recurrence of retroperitoneal sarcomas (RPS) and correlate to clinical treatment volumes of postoperative radiation therapy (PORT) with or without intraoperative radiation therapy (IORT).

Methods: A retrospective review of patients with RPS who received PORT between 1990 and 2008 was done. Tumor recurrences were subdivided as local tumor bed, regional adjacent retroperitoneal fascial tissues, peritoneal diffuse seeding, and distant metastases.

Results: PORT was given to 33 patients, 20 of whom also received IORT. Local recurrences appeared in 4 (12%) cases. Regional recurrences appeared in 8 (26%) cases, including 5 with in-field recurrence and 3 with edge-of-field recurrence. Edge-of-field recurrences developed in 3 of 11 (27%) patients whose clinical presentation was local recurrence compared with none of 20 patients whose clinical presentation was a primary tumor (P=0.037). Late grades 3 to 4 gastrointestinal toxicities appeared in 1 of 10 (10%) patients who received intensity-modulated radiation therapy (IMRT) with a minimum 15-month follow-up compared with 4 of 15 (27%) patients who received standard RT.

Conclusions: Use of techniques such as IORT and IMRT can deliver a dose of approximately 60 Gy to the tumor bed and 44 to 51 Gy to the surrounding retroperitoneal fascial planes. Acute and late gastrointestinal toxicities were less frequent with IMRT compared with conventional PORT with IORT. These results may provide the basis for comparison of various adjuvant therapy strategies for RPS. As radiation therapy is a loco-regional treatment, results should be reported by tumor recurrence subtypes of local, regional, peritoneal, and distant.