18F-FDG PET/CT-Informed Multidisciplinary Reassessment Modifies Surgical Strategy in Patients with Metastatic Bone Disease: Exploratory Predictors of Decision Change in an Orthopedic Oncology Board

Background/Objectives: Bone is the third most common site of solid-tumor metastasis, and surgical management spans a wide spectrum from observation to curative en bloc resection in selected patients. 18F-FDG PET/CT has been reported to alter oncologic management in 20% to 45% of patients across diverse settings, yet its specific impact on surgical decision-making within a multidisciplinary orthopedic oncology board (MOOB) reassessment and the predictors of decision change remain undefined. Methods: We retrospectively analyzed consecutive patients with histopathologically confirmed bone metastases evaluated at a tertiary-care MOOB between February 2023 and February 2026. For each patient, the surgical plan was recorded twice: first by the orthopedic team based on available conventional imaging (radiography, computed tomography, magnetic resonance imaging) and then as the final PET/CT-informed MOOB review. This design evaluates changes in decision-making intent after PET/CT-informed multidisciplinary reassessment, rather than the isolated causal effect of PET/CT or actual surgical implementation. Surgical plans were categorized as no surgery, palliative stabilization, palliative resection, or curative-intent resection, and changes were classified as no change, escalation, de-escalation, or cancellation. Results: Among 73 patients (mean age 64.7 ± 12.1 years; 53.4% male), the most frequent primaries were lung (37.0%), breast (21.9%), and renal cell carcinoma (13.7%). Following PET/CT-informed MOOB reassessment, the intended surgical plan changed in 53.4% of cases (p < 0.001), comprising surgery cancellation (27.4%), escalation (17.8%), and de-escalation (8.2%). Patients directed to no surgery increased fourfold (6.8% to 28.8%), and curative resection emerged as a post-reassessment recommendation (0% to 10.9%). SUVmax did not predict overall decision change, but higher SUVmax was associated with cancellation/de-escalation in the directional analysis. In exploratory multivariable analysis, polymetastatic disease (OR 0.051; 95% CI 0.005 to 0.547; p = 0.014), long-bone diaphyseal location (OR 0.133; p = 0.006), and higher Eastern Cooperative Oncology Group (ECOG) performance score (OR 2.109 per point; p = 0.018) independently predicted decision change. Conclusions: PET/CT-informed MOOB reassessment was associated with substantial changes in intended surgical strategy for metastatic bone disease. The findings support careful multidisciplinary integration of metabolic imaging, metastatic burden, anatomic location, and performance status, but should be regarded as hypothesis-generating until validated prospectively with data on treatment delivery and downstream outcomes.