Dual time point 18F-fluorodeoxyglucose positron emission tomography/computed tomography fusion imaging (18F-FDG PET/CT) in primary breast cancer

Abstract

Background: To evaluate the clinicopathological and prognostic significance of the percentage change between maximum standardized uptake value (SUVmax) at 60 min (SUVmax1) and SUVmax at 120 min (SUVmax2) (ΔSUVmax%) using dual time point 18F-fluorodeoxyglucose emission tomography/computed tomography (18F-FDG PET/CT) in breast cancer. Methods: Four hundred and sixty-four patients with primary breast cancer underwent 18F-FDG PET/CT for preoperative staging. ΔSUVmax% was defined as (SUVmax2 - SUVmax1) / SUVmax1 × 100. We explored the optimal cutoff value of SUVmax parameters (SUVmax1 and ΔSUVmax%) referring to the event of relapse by using receiver operator characteristic curves. The clinicopathological and prognostic significances of the SUVmax1 and ΔSUVmax% were analyzed by Cox's univariate and multivariate analyses. Results: The optimal cutoff values of SUVmax1 and ΔSUVmax% were 3.4 and 12.5, respectively. Relapse-free survival (RFS) curves were significantly different between high and low SUVmax1 groups (P = 0.0003) and also between high and low ΔSUVmax% groups (P = 0.0151). In Cox multivariate analysis for RFS, SUVmax1 was an independent prognostic factor (P = 0.0267) but ΔSUVmax% was not (P = 0.152). There was a weak correlation between SUVmax1 and ΔSUVmax% (P < 0.0001, R 2 = 0.166). On combining SUVmax1 and ΔSUVmax%, the subgroups of high SUVmax1 and high ΔSUVmax% showed significantly worse prognosis than the other groups in terms of RFS (P = 0.0002). Conclusion: Dual time point 18F-FDG PET/CT evaluation can be a useful method for predicting relapse in patients with breast cancer. The combination of SUVmax1 and ΔSUVmax% was able to identify subgroups with worse prognosis more accurately than SUVmax1 alone.