(P 466) INTRAOPERATIVE EVALUATION OF BONE AND SOFT TISSUE SARCOMA SURGICAL MARGINS WITH INDOCYANINE GREEN FLUORESCENCE IMAGING

Objective: Achieving negative surgical margins is the cornerstone of bone and soft tissue sarcoma management, with positive margins portending a high risk of local recurrence (LR) and overall poor prognosis. Indocyanine green (ICG) is a fluorophore dye which has been utilized intraoperatively to evaluate surgical margins in several malignancies, including breast and gastrointestinal cancers. Given the critical importance of achieving negative margins in sarcomas, ICG fluorescence imaging has the potential to become a valuable intraoperative margin assessment tool for these uncommon and difficult-to-treat cancers. This study sought to evaluate ICG fluorescence imaging’s utility in bone and soft tissue sarcoma resection.

Methods: This prospective non-randomized clinical trial included patients with biopsy-confirmed bone or soft tissue sarcomas undergoing surgical resection. Exclusion criteria included age < 18 years, prior adverse reaction to iodine or fluorescein, and renal disease. Patients received an intravenous ICG infusion dosed at 2.0 mg/kg three hours preoperatively. Intraoperatively, the removed tumor and tumor bed were imaged using a SPY-PHI fluorescent camera (Stryker Co.; Kalamazoo, MI). ICG-positive margins were defined as regions of tumor bed with a fluorescence intensity ≥77% of the resected tumor’s highest measured intensity (Image 1). Sensitivity and specificity were compared between ICG margins, final pathology, and the surgeon’s blinded clinical impression. Cases where ICG matched or did not match final pathology were then grouped and compared using Student’s t-test and Fisher’s exact test (alpha = 0.05).

Results: 37 sarcoma (7 bone, 30 soft tissue) patients have been enrolled (Figure 1). ICG margins matched final pathology in 67.6% (25/37) of cases, with 23.1% sensitivity and 91.7% specificity (Figure 2). Surgeon impression matched final pathology in 59.4% (22/37) of cases, with 15.4% sensitivity and 83.3% specificity. No significant differences were found in ICG infusion time, infusion to incision time, or dosage between cases when ICG correctly or incorrectly matched final pathology (Figure 3). The presence of pre-operative radiation (10/37), pre-operative chemotherapy (5/37), or recurrent sarcoma (6/37) also did not significantly affect ICG margins when compared to final pathology margins.

Conclusion: ICG fluorescence imaging shows potential as an intraoperative margin assessment tool in sarcoma resection. Larger sample sizes and longer follow-up are needed to optimize dosing, infusion timing, and disease factors influencing this technique’s accuracy in sarcoma patients. Investigating the effects of histological subtype, chemotherapy, and radiation will also contribute to our understanding of how ICG fluorescence imaging can be optimized to help surgeons resect sarcomas effectively.