The Utility of Positron Emission Tomography (PET) with 18Fluorodeoxyglucose (18F-FDG) Compared to Standard Procedures in Detecting Bone Marrow Infiltration in Diffuse Large B-Cell Lymphoma in Developing Countries.

Abstract 5015 Background Computed tomography (CT) scanning and bone marrow biopsy (BMB) are the most used methods for initial staging in Diffuse Large B-cell Lymphoma (DLBCL) in developing countries. In the United States and Europe, 18-FDG PET has demonstrated to be an essential imaging modality for initial staging, early response and final therapeutic assessment in DLBCL patients. Afterward BM biopsy (BMB) is the gold standard to detect BM infiltration in lymphoma. However the ability of the FDG-PET to assess bone marrow (BM) positivity in DLBCL has been investigated and remains a controversial issue in the literature. For that reason we retrospectively compared the BM infiltration by bilateral BMB with FDG-PET at diagnosis in DLBCL patients. Methods We evaluated retrospectively 38 patients with DLBCL reporting the number of true-positive, false-positive, true-negative, and false-negative BM positivity by FDG-PET having the bilateral BMB as a reference standard. Results Out of 38, BM(+) was detected in 4 (10.5%) patients by BMB and in 14 (36.8%) patients by FDG-PET. The sensitivity and specificity of FDG-PET to recognize BM infiltration were respectively 100% and 71%. Negative and positive predictive values of the FDG-PET to identify BM(+) were respectively 100% and 28.5%. In negative-BMB patients, a positive FDG-PET BM was found in iliac 1 (10%), vertebra 5 (50%), sternum 2 (20%), scapula 1 (10%) and femur 1 (10%). The 18FDG mean maximum standardized uptake value (SUVmax) was 6.85 ± 3.9 in negative-BMB group and 9.77 ± 3.2 in positive-BMB group, p=0,208. Conclusion These results suggest that FDG-PET has a good sensitivity in detecting bone marrow infiltration in this type of aggressive lymphoma when compared to bilateral BMB to our knowledge the standard procedure to evaluate BM infiltration in lymphoma staging. Even though this study has several limitations such as one single center experience, a small number of patients and the lack of FDG-PET BM(+) confirmation by guided biopsy in previously negative-BMB patients, the majority of publications have been made in developed countries, and moreover we believe many issues still remain to be answered such as data regarding the FDG-PET cost-effectiveness out of clinical trails, specially in developing countries, in order to elucidate whether these results will be translated into a real benefit in overall survival for these patients. Disclosures No relevant conflicts of interest to declare.