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 (SUV.sub.max) at 60 min (SUV.sub.max1) and SUV.sub.max at 120 min (SUV.sub.max2) ([DELA]SUV.sub.max%) using dual time point .sup.18F-fluorodeoxyglucose emission tomography/computed tomography (.sup.18F-FDG PET/CT) in breast cancer. Methods Four hundred and sixty-four patients with primary breast cancer underwent .sup.18F-FDG PET/CT for preoperative staging. [DELA]SUV.sub.max% was defined as (SUV.sub.max2 - SUV.sub.max1) / SUV.sub.max1 x 100. We explored the optimal cutoff value of SUV.sub.max parameters (SUV.sub.max1 and [DELA]SUV.sub.max%) referring to the event of relapse by using receiver operator characteristic curves. The clinicopathological and prognostic significances of the SUV.sub.max1 and [DELA]SUV.sub.max% were analyzed by Cox's univariate and multivariate analyses. Results The optimal cutoff values of SUV.sub.max1 and [DELA]SUV.sub.max% were 3.4 and 12.5, respectively. Relapse-free survival (RFS) curves were significantly different between high and low SUV.sub.max1 groups (P = 0.0003) and also between high and low [DELA]SUV.sub.max% groups (P = 0.0151). In Cox multivariate analysis for RFS, SUV.sub.max1 was an independent prognostic factor (P = 0.0267) but [DELA]SUV.sub.max% was not (P = 0.152). There was a weak correlation between SUV.sub.max1 and [DELA]SUV.sub.max% (P < 0.0001, R.sup.2 = 0.166). On combining SUV.sub.max1 and [DELA]SUV.sub.max%, the subgroups of high SUV.sub.max1 and high [DELA]SUV.sub.max% showed significantly worse prognosis than the other groups in terms of RFS (P = 0.0002). Conclusion Dual time point .sup.18F-FDG PET/CT evaluation can be a useful method for predicting relapse in patients with breast cancer. The combination of SUV.sub.max1 and [DELA]SUV.sub.max% was able to identify subgroups with worse prognosis more accurately than SUV.sub.max1 alone. Keywords: Dual time point, [DELA]SUV.sub.max%, Primary breast cancer