Prognostic value of fluorine(18) flourodeoxyglucose positron emission tomography/computed tomography in dogs with appendicular osteosarcoma

BACKGROUND: Factors indicative of a negative prognosis for appendicular osteosarcoma (OSA) in dogs are visible metastatic disease, location, and size of lesion. In human medicine maximum standard uptake value (SUV(max)), as measured on a fluorine(18) flourodeoxyglucose positron emission tomography/computed tomography ((18)F‐FDG PET/CT), is prognostic for survival for several tumor types. OBJECTIVE: Determine if SUV(max) is associated with progression‐free interval (PFI) and determination of survival in dogs with appendicular OSA. ANIMALS: Sixty‐two dogs with untreated appendicular OSA that had been staged with (18)F‐FDG PET/CT. METHODS: Retrospective analysis of the (18)F‐FDG PET/CT was performed. Dogs were excluded from the study if they did not receive definitive intent treatment for their primary OSA and adjuvant chemotherapy with carboplatin, or had visible metastatic disease on initial imaging. A region of interest (ROI) was created around the primary tumor to measure SUV(max). Univariable and multivariable Cox proportional hazards analysis was performed to evaluate for associations between variables including SUV(max) and outcome of PFI and overall survival (OS). RESULTS: Maximum standard uptake value of the primary tumor was significantly associated with the OS (P = .04) with adjustment for treatment type and monocyte count. The overall median survival time (OST) was 284 days (range, 39‐1293 days) with the OST of dogs having an SUV(max) of ≥7.4 of 254 days (range, 98‐428 days) and dogs with an SUV(max) of <7.4 of 680 days (range, 108‐811 days, P = .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Maximum standard uptake value as measured via (18)F‐FDG PET/CT is significantly associated with survival in dogs with appendicular OSA with a high SUV(max) being an indicator of a negative prognosis.