Treatment of Retroperitoneal Fibrosis

Diagnostic Approach

Biopsy is mandatory to definitively distinguish malignant from benign retroperitoneal fibrosis, as imaging alone cannot reliably differentiate between the two entities, according to the National Comprehensive Cancer Network 1
Image-guided core needle biopsy is preferred over open surgical biopsy to establish diagnosis and histologic subtype, as recommended by the National Comprehensive Cancer Network 1
The differential diagnosis must exclude lymphoma and germ cell tumors, which would require completely different treatment approaches, as stated by the National Comprehensive Cancer Network and the British Journal of Cancer 1, 2, 3

Complete surgical resection with negative margins is the only curative treatment and must be performed at primary presentation by surgeons with sarcoma expertise, as recommended by the British Journal of Cancer and the National Comprehensive Cancer Network 1, 3
The surgical extent depends on histologic subtype, with extended resection including adjacent viscera for liposarcomas and complete tumor resection with involved organs only for leiomyosarcomas, as stated by the British Journal of Cancer 3
Neoadjuvant radiotherapy (45-50 Gy) is often preferred as it reduces tumor seeding risk and may improve resectability, according to the British Journal of Cancer and the National Comprehensive Cancer Network 3, 4, 5
Neoadjuvant chemotherapy may be considered when response would facilitate resection or improve symptoms, as recommended by the National Comprehensive Cancer Network 5
Histology-specific targeted therapies should be considered for appropriate subtypes, as stated by the British Journal of Cancer 3

For malignant retroperitoneal fibrosis, cross-sectional imaging at 3-6 month intervals initially, extending to annual after 5 years, is recommended to detect asymptomatic recurrences, as stated by the British Journal of Cancer and the National Comprehensive Cancer Network 3, 4

Never proceed with major surgical resection before establishing the diagnosis with biopsy, as this prevents inappropriate resection of lymphoma, germ cell tumors, or benign inflammatory conditions that require medical rather than surgical management, as recommended by the National Comprehensive Cancer Network and the British Journal of Cancer 1, 2, 3

Postoperative boost radiation (10-12.5 Gy IORT for microscopically positive margins, 15 Gy for gross disease) may be considered following complete resection, as per the National Comprehensive Cancer Network 6

For retroperitoneal liposarcomas, extended surgical resection including adjacent viscera is required due to poorly defined margins, and may necessitate ipsilateral nephrectomy, hemicolectomy, psoas fascia/muscle resection, and potentially distal pancreatectomy/splenectomy 6
For solitary fibrous tumors, complete resection with negative margins while preserving uninvolved organs is recommended 6