(P 71) LIMB-SALVAGE SURGERY AFTER UNPLANNED SURGERY FOR EXTREMITY BONE SARCOMAS: 30-YEAR EXPERIENCE AT A TERTIARY REFERRAL CENTER

Objective: Bone sarcomas are rare and can mimic other entities, such as benign lesions or usual fractures. Subsequently, bone sarcomas can occasionally be operated on without recognition or under incorrect diagnosis (unplanned surgery). The tumour cells may be spread into the surrounding tissue after unplanned surgeries, which can render limb-salvage surgery challenging and can be associated with a worse outcome. In this study, we investigated the following questions: 1) What is the pattern of unplanned surgeries for bone sarcoma? 2) Who received limb-salvage surgery? 3) What are the oncologic outcomes?

Methods: This was a single-center retrospective study. All patients from 1992 to 2023 presenting with extremity bone sarcoma after unplanned surgery and undergoing surgical treatment in our institution were included. The demographics and details of unplanned surgeries were analyzed. The local recurrence and disease-specific survival were compared between the limb-salvage and amputation groups.

Results: In total, 46 patients were included, accounting for 4% of all the bone sarcomas surgically treated during the period. Limb-salvage surgery was performed on 57% (26/46). The median follow-up was 63 months (IQR, 15–147). Of these patients, 37% (17/46) had chondrosarcoma, 30% (14/46) had osteosarcoma, and the remaining had other bone sarcomas. They were initially diagnosed to be benign lesions in 48% (22/46), usual fractures in 28% (13/46), osteoarthritis in 13% (6/46), and metastatic carcinoma in 11% (5/46). Femur was the most common location (67%, 31/46), followed by tibia (9%, 4/46), hand or foot (10%, 5/46), and others (14%, 6/46). The backgrounds of the limb-salvage group and amputation group significantly differed in tumour size (median 8 cm (IQR, 6–12) versus 14 cm (IQR, 9–21), p=0.02), and rate of low-grade tumour (23% (6/26) vs. 0% (0/20), p=0.03). The type of unplanned surgery is shown in Table 1. The arthroplasty group had the highest rate of amputation. Of the 11 intramedullary nail cases, limb-salvage surgeries were only performed on the femurs (6/8) but not the humerus (0/2) and the tibia (0/1).
Between the limb-salvage and amputation groups, the 5-year local recurrence-free survival was similar among the groups (91% (95%CI, 68–98) versus 91% (95%CI, 51–99), p>0.99). On the other hand, the 5-year disease-specific survival was better in the limb-salvage group (84% (95%CI, 63–94) versus 48% (95%CI, 25–68), p=0.002) without controlling for tumour size and pathology grade. After excluding the low-grade sarcomas (n=6, all in the limb-salvage group), the 5-year disease-specific survival was still better in the limb-salvage group (79% (95%CI, 53–92) versus 48% (95%CI, 25–68), p=0.01).

Conclusion: Incorrect diagnoses as benign tumours were the most common cause of unplanned surgery in patients with extremity bone sarcomas. Unplanned surgery for larger tumours and more contaminating procedures, such as arthroplasty and intramedullary nails in the humerus and tibia, may render limb-salvage surgery unfeasible. Limb-salvage surgery was not associated with a higher local recurrence rate with our cohort size and may be considered whenever possible.