Neoadjuvant Radiotherapy for R0 Resection in Intermediate-Grade Fibrosarcoma
Yes, preoperative external-beam radiotherapy at 50 Gy in 25-28 fractions significantly increases the likelihood of achieving R0 resection in your patient with intermediate-grade fibrosarcoma of the proximal femoral shaft invading the hip joint capsule, and should be strongly recommended. 1
Evidence for Improved R0 Resection Rates
Neoadjuvant radiotherapy independently predicts higher rates of R0 resection compared to surgery alone or postoperative radiotherapy. In a large national database analysis of 27,969 extremity soft tissue sarcoma patients, preoperative RT achieved 90.1% R0 resection rates versus 74.9% with postoperative RT and 79.9% with surgery alone (P < 0.001). 2 Preoperative RT was an independent predictor of R0 resection with an odds ratio of 1.83 (95% CI 1.61-2.07). 2
The mechanism is clear: preoperative treatments are specifically intended to improve the quality of surgical margins, not to change the extent of surgery. 3 This is particularly relevant for your case where the tumor invades the hip joint capsule—a critical anatomical structure where achieving wide margins would otherwise require extensive functional compromise or amputation.
Standard Neoadjuvant Protocol
Deliver 50 Gy in 25-28 fractions (1.8-2 Gy per fraction) over 5-6 weeks, followed by definitive surgery 4-8 weeks after completion. 1 This represents the guideline-endorsed standard approach from both NCCN and ESMO. 1
The lower total dose compared to postoperative RT (which requires 60-66 Gy) is possible because the tumor is better oxygenated preoperatively and treatment volumes are smaller. 1
Specific Advantages for Your Case
For intermediate-grade tumors >5 cm that are deep (which applies to proximal femoral shaft lesions), neoadjuvant or adjuvant radiotherapy is the standard of care. 3 Your patient's tumor invading the hip capsule makes this a borderline resectable case where neoadjuvant radiotherapy is strongly favored because negative surgical margins are uncertain. 1
The preoperative approach offers smaller treatment volumes since you don't need to encompass the entire operative field, reducing exposure of normal tissues including the femoral neurovascular bundle and adjacent pelvic structures. 1 This is critical for preserving limb function.
Preoperative RT mitigates the adverse impact of R1 margins more effectively than postoperative radiotherapy, 1 which is essential when resecting around the hip joint capsule where achieving wide margins may be anatomically impossible without hip disarticulation.
Managing Surgical Margins After Neoadjuvant RT
After preoperative RT and resection, close but negative margins (<1 mm from tumor) appear sufficient for local control in high-grade pleomorphic sarcomas treated with neoadjuvant therapy, with minimal reduction in local recurrence risk with increasing margin width. 4 This finding supports accepting closer margins when critical structures are involved.
If microscopic (R1) positive margins occur despite preoperative RT, add a boost of 16-18 Gy. 1 For gross residual disease (R2), boost with 20-26 Gy. 1 However, when wide negative margins are achieved following preoperative RT, no additional radiation is required. 1
Critical Caveat: Wound Complications
The primary tradeoff is doubled risk of acute wound-healing complications with neoadjuvant RT. 5 To mitigate this, involve plastic surgery expertise for complex closures, 1 particularly important in the proximal thigh/hip region where large dead space and tension on closures are concerns.
Modern IMRT techniques may lower historically reported wound complication rates. 1 The 4-8 week interval between RT completion and surgery is designed to allow acute radiation effects to resolve while avoiding excessive delays that increase late fibrosis. 1
Long-Term Functional Outcomes
Preoperative RT is associated with reduced long-term morbidity including lower rates of fibrosis, edema, pathological fractures, and joint stiffness compared to postoperative RT. 1 This superior functional outcome, combined with equivalent disease control, makes the preoperative approach preferable for limb-sparing surgery in your patient. 3
Multidisciplinary Requirement
This case must be discussed in a sarcoma multidisciplinary tumor board that includes pathology, radiology, surgery, and radiation oncology before proceeding. 3, 1 Treatment planning should occur at a dedicated sarcoma reference center, as care outside expert facilities is associated with higher positive-margin rates. 1