Preoperative [18F] FDG-PET after chemotherapy in locally advanced breast cancer: prognostic value as compared with histopathology

Background: Established prognosis-based criteria determine the need for further treatment after primary surgery for breast cancer. Such criteria are lacking after neo-adjuvant chemotherapy. We determine the prognostic value of preoperative [F-18]-2-fluoro-2-deoxy-D-glucose-positron emission tomography ((18)FDG-PET) after chemotherapy in locally advanced breast cancer (LABC), both as independent indicator and as add-on to postoperative histopathology. Patients and methods: Preoperative PET was carried out in 40 LABC patients. Two expert readers assessed residual (18)FDG uptake in the primary tumor. At histopathological examination of the surgical specimen, chemotherapy response was graded using the Honkoop criteria. Cox proportional hazards analysis was used to determine prognostic relevance of PET and histopathology. Results: Median follow-up was 60 months (range 15-94), during which 13 patients had recurrent disease, eight of whom died. (18)FDG uptake in the primary tumor was inversely related with disease-free survival (DFS) [hazard ratio (HR) 4.09; 95% confidence interval (CI) 1.26-13.31; P = 0.02] and this was superior to histopathology (HR 2.52; 95% CI 0.77-8.23; P = 0.13). Observer agreement of PET was excellent (intraclass correlation coefficient 0.88). Multivariate Cox regression revealed no added value of histopathology versus PET results. Conclusion: (18)FDG uptake in the primary tumor at PET was inversely associated with DFS and may help to guide adjuvant therapy.