Significance of Metabolic Tumor Volume at Baseline and Reduction of Mean Standardized Uptake Value in (18)F-FDG-PET/CT Imaging for Predicting Pathological Complete Response in Breast Cancers Treated with Preoperative Chemotherapy

BACKGROUND: The usefulness of (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography for evaluating the treatment efficacy of breast cancers is well-established; however, the predictive values of parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) remain unknown. METHODS: This study examined 199 breast cancers treated with primary systemic chemotherapy (PSC) followed by operation, and determined the values of maximum standardized uptake value (SUV(max)), peak SUV (SUV(peak)), mean SUV (SUV(mean)), MTV, and TLG at baseline. Among these cases, data on early changes in these metabolic parameters in 70 breast cancers were also assessed. RESULTS: A pathological complete response (pCR) was achieved in 64 breast cancers. Breast cancers with low MTV at baseline had a significantly higher pCR rate than breast cancers with high MTV (47.9% vs. 23.4%; p = 0.0005). High reduction rates (∆) of SUV(max) (p = 0.0001), SUV(peak) (p = 0.0001), and SUV(mean) (p < 0.0001) resulted in an increased pCR compared with those for low ∆. The pCR rate was highest for the combination of low MTV and high ∆SUV(mean) (86.7%), and lowest for high MTV and low ∆SUV(mean) (15.4%); the remaining combinations were intermediate (58.6%; p < 0.0001). The combination of low MTV at baseline and high ∆SUV(mean) was a significant and independent predictor for pCR (odds ratio 28.63; 95% confidence interval 1.94–422.42; p = 0.0146) in multivariable analysis. CONCLUSIONS: Low levels of MTV at baseline and a high reduction of SUV(mean) after PSC was significantly associated with pCR. These findings suggest the usefulness of these metabolic parameters for predicting the treatment efficacy of breast cancers. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1245/s10434-019-07325-8) contains supplementary material, which is available to authorized users.