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

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