Value of Dynamic ¹⁸F-FDG PET/CT in Predicting the Success of Neoadjuvant Chemotherapy in Patients with Locally...

This prospective study was planned to compare the predictive value of dynamic ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in locally advanced breast cancer patients (LABC) receiving neoadjuvant chemotherapy (NAC).

Twenty seven patients with LABC [median age: 47, (26-66)] underwent a dynamic ¹⁸F-FDG PET study at baseline, and after 2-3 cycles of (NAC) were included (interim). Maximum standardized uptake value (SUV_max) values and SUV ratios for the 2^nd, 5^th, 10^th, and 30^th minutes and dynamic curve slope (SL) values and SL ratios were measured using ¹⁸F-FDG dynamic data. In addition, the values of SUV_mean (2minSUVmean), SULpeak (2minSULpeak), metabolic volume (2minVol), and total lesion glycolysis (2minTLG) were measured for the first 2 min. Percent changes between baseline and interim studies were calculated and compared with the pathological results as the pathological complete response (PCR) or the pathological non-complete response (non-PCR). Receiver operating characteristic curves were obtained to calculate the area under the curve to predict PCR. Optimal threshold values were calculated to discriminate between PCR and non-PCR groups.

Baseline study SUV 30 (p=0.044), SUV 30/2 (p=0.041), SUV 30/5 (p=0.049), SUV 30/10 (p=0.021), SL 30/2 (p=0.029) and SL 30/5 (p=0.027) values were statistically significant different between PCR and non-PCR groups. The percentage changes of 2minVol between PCR and non-PCR groups were statistically significant. For the threshold value of -67.6% change in 2minVol, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.2%, 77.8%, 63.6%, 93.3%, and 80.7%, respectively (area under the curve: 0.826, p=0.009).

Semiquantitative parameters for dynamic ¹⁸F-FDG PET can predict PCR. % changes in 2minVol can identify non-responding patients better than other parameters.