Response to neoadjuvant chemotherapy is 1 of the most powerful prognostic factors for extremity osteosarcoma. [F-18]-fluorodeoxy-D-glucose–positron emission tomography (FDG-PET) is a noninvasive imaging modality that is used to predict histopathologic response. To determine the prognostic value of FDG-PET response for progression-free survival (PFS) in osteosarcoma, the authors of this report reviewed the University of Washington Medical Center experience.
Forty patients with extremity osteosarcoma were evaluated by FDG-PET. All patients received neoadjuvant and adjuvant chemotherapy. FDG-PET standard uptake values (SUVs) before neoadjuvant chemotherapy (SUV1) and after neoadjuvant chemotherapy (SUV2) were analyzed and correlated with histopathologic response.
The median SUV1 was 6.8 (range, 3.0-24.1), the median SUV2 was 2.3 (range, 1.2-12.8), and the median SUV2 to SUV1 ratio (SUV2:1), was 0.36 (range, 0.12-1.10). A good FDG-PET response was defined as anSUV2 <2.5 or an SUV2:1 ≤0.5. FDG-PET responses according to SUV2 and SUV2:1 were concordant with histologic response in 58% and 68% of patients, respectively. SUV2 was associated with outcome (4-year PFS, 73% for SUV2 <2.5 vs 39% for SUV2 ≥2.5; P = .021). Both the initial disease stage and the histologic response were associated with outcome.
FDG-PET imaging of extremity osteosarcoma was correlated only partially with a histologic response to neoadjuvant chemotherapy. An SUV2 <2.5 was associated with improved PFS. Future prospective studies are warranted to determine whether FDG-PET imaging may be used as a predictor of outcome independent of initial disease stage. Cancer 2009. © 2009 American Cancer Society.