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

Background To evaluate the clinicopathological and prognostic significance of the percentage change between maximum standardized uptake value (SUVmax) at 60 min (SUV(max)1) and SUVmax at 120 min (SUV(max)2) (Delta SUVmax%) using dual time point F-18-fluorodeoxyglucose emission tomography/computed tomography (F-18-FDG PET/CT) in breast cancer. Methods Four hundred and sixty-four patients with primary breast cancer underwent F-18-FDG PET/CT for preoperative staging. Delta SUVmax% was defined as (SUV(max)2 - SUV(max)1) / SUV(max)1 x 100. We explored the optimal cutoff value of SUVmax parameters (SUV(max)1 and Delta SUVmax%) referring to the event of relapse by using receiver operator characteristic curves. The clinicopathological and prognostic significances of the SUV(max)1 and Delta SUVmax% were analyzed by Cox's univariate and multivariate analyses. Results The optimal cutoff values of SUV(max)1 and Delta SUVmax% were 3.4 and 12.5, respectively. Relapse-free survival (RFS) curves were significantly different between high and low SUV(max)1 groups (P = 0.0003) and also between high and low Delta SUVmax% groups (P = 0.0151). In Cox multivariate analysis for RFS, SUV(max)1 was an independent prognostic factor (P = 0.0267) but Delta SUVmax% was not (P = 0.152). There was a weak correlation between SUV(max)1 and Delta SUVmax% (P < 0.0001, R-2 = 0.166). On combining SUV(max)1 and Delta SUVmax%, the subgroups of high SUV(max)1 and high Delta SUVmax% showed significantly worse prognosis than the other groups in terms of RFS (P = 0.0002). Conclusion Dual time point F-18-FDG PET/CT evaluation can be a useful method for predicting relapse in patients with breast cancer. The combination of SUV(max)1 and Delta SUVmax% was able to identify subgroups with worse prognosis more accurately than SUV(max)1 alone.