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.