18F-FDG PET/CT for early prediction of response to neoadjuvant chemotherapy in breast cancer.

Purpose: The aim of this study was to prospectively evaluate 18F-FDG PET/CT in predicting response to neoadjuvant chemotherapy in large primary breast cancer.

Methods: Fifty consecutive patients underwent PET/CT at baseline and after the second cycle. Baseline MRI was performed to establish tumour size. All findings were confirmed by histopathological analysis. Changes in maximum standardized uptake value (SUV(max)) between baseline study and after two cycles of neoadjuvant chemotherapy (epirubicin + cyclophosphamide + taxanes) were compared using response evaluation criteria in solid tumours (RECIST) criteria and the Miller and Payne (M&P) scale.

Results: The mean tumour size was 4.3 +/- 1.4 cm. Forty patients were considered responders and ten as non-responders. SUV(max) changes in patients with good prognosis (M&P grades 4-5) were higher than in patients with bad prognosis (M&P grades 1-3) (p = 0.025). SUV(max) changes between responders and non-responders following RECIST criteria were also statistically significant (p = 0.0028). A cut-off DeltaSUV value of 40% differentiates both groups, with a sensitivity of 77% and a specificity of 80%.

Conclusion: 18F-FDG PET/CT can predict response to neoadjuvant chemotherapy at an early stage.