In newly diagnosed diffuse large B-cell lymphoma (DLBCL), the sensitivity of bone marrow biopsy (BMB) for the detection of bone marrow involvement (BMI) can be low because of sampling error if the BMI is focal and not diffuse. Although (18)F-FDG PET/CT is now recommended for initial staging of DLBCL, its role regarding BMI is not well defined. This study evaluated whether (18)F-FDG PET/CT, in comparison with BMB, is useful for the detection of BMI and predictive of outcome.
Methods: From the 142 patients who were referred to our institution for newly diagnosed DLBCL from June 2006 to October 2011, 133 were retrospectively enrolled in our study. All patients underwent whole-body (18)F-FDG PET/CT and a BMB from the iliac crest before any treatment. (18)F-FDG PET/CT was considered positive for BMI in cases of uni- or multifocal bone marrow (18)F-FDG uptake that could not be explained by benign findings on the underlying CT image or history. A final diagnosis of BMI was considered if the BMB was positive or if the positive (18)F-FDG PET/CT was confirmed by guided biopsy or targeted MR imaging or in cases of disappearance of focal bone marrow uptake concomitant with the disappearance of uptake in other lymphoma lesions on (18)F-FDG PET/CT monitoring. Progression-free survival and overall survival were analyzed using the Cox proportional hazards regression model.
Results: Thirty-three patients were considered to have BMI. Of these, 8 were positive according to the BMB and 32 were positive according to (18)F-FDG PET/CT. (18)F-FDG PET/CT was more sensitive (94% vs. 24%; P < 0.001), showed a higher negative predictive value (98% vs. 80%), and was more accurate (98% vs. 81%) than BMB. Median follow-up was 24 mo (range, 1-67 mo). Twenty-nine patients (22%) experienced recurrence or disease progression during follow-up, and 20 patients died (15%). In multivariate analysis, only the International Prognostic Index and the (18)F-FDG PET/CT bone marrow status were independent predictors of progression-free survival (P = 0.005 and 0.02, respectively), whereas only the International Prognostic Index remained an independent predictor of overall survival (P = 0.004).
Conclusion: Assessment of BMI with (18)F-FDG PET/CT provides better diagnostic performance and prognostic stratification in newly diagnosed DLBCL than does BMB.
Keywords: PET/CT; biopsy; bone marrow; diffuse large B-cell lymphoma.