Utility of PET-CT for assessment of response to neo-adjuvant chemotherapy in breast cancer.

12 Background: Response to neo-adjuvant chemotherapy (NACT) is associated with prognosis in non-metastatic breast cancer and can potentially inform further therapeutic options. The aim of this study was to correlate post NACT response on PET CT with pathological response. Methods: All patients who underwent pre- NACT (baseline) and post NACT PET CT imaging with F-18 FDG in a dose of 5-7 MBq/kg body weight with a minimum of 185 MBq given intravenously were retrospectively analyzed. Scan was performed on GE Discovery 710 whole-body PET scan with 128 slice CT. Relevant clinical and imaging related details were extracted from the treatment records. Post NACT PET response (PERCIST criteria) in the primary tumor and nodes was correlated with the pathological response on the post surgical specimen. Analysis was done using Microsoft Excel and SPSS v20 (IBM SPSS). Results: The median age was 49 years (range 30-76 years). 83.1% of patients had node positive disease on baseline PET imaging (not pathologically confirmed). Post chemotherapy PET showed complete metabolic response in the primary tumor and regional nodes in 56.3% and 74% of patients respectively. Two patients had progressive local disease. Pathological complete response rates post surgery in triple negative, Her2 neu positive and ER positive group was 50%, 34% and 12% respectively. The sensitivity, specificity, positive predictive value and negative predictive value is tabulated below. Conclusions: Overall FDG PET CT showed good specificity with limited sensitivity for post NACT response assessment in breast cancer. Our results suggest that post NACT PET CT may have limited utility for clinical decision making and at present its use cannot be recommended outside of a clinical trial.[Table: see text]