High risk breast cancer: prospective data about the role of FDG PET/CT in pre- and post-operative settings

Purpose: who should be evaluated initially with 18F-fluorodeoxyglucose (FDG) hybrid positron emission tomography/computed tomography (PET/CT) among breast cancer patients? For providing an answer to this question, herein we aimed to determine the potential diagnostic and therapeutic impact of pre and post-operative FDG PET/CT in patients with breast cancer at high risk of recurrence. Materials and methods: we prospectively collected data from 165 women (age: 53±12 yrs; range:23-82 yrs) with a locally advanced breast cancer diagnosis at initial staging or after surgical treatment (clinical or pathological stage II-III, respectively) who performed FDG PET/CT examination before (n=85) or after surgery (n=80). The mean period between surgery and PET/CT was 45±22 days. The images were visually and semiquantitatively analyzed and compared with other imaging modalities, biopsy or histology, as appropriate. The treatment was planned by the oncologists, according to the current recommendation. The diagnostic performance was calculated by standard methods. The differences between categorical data were assessed using Yates-corrected chi-square test. Results: FDG PET/CT was negative in 43 out of 80 (53.75%) post-operative subjects, while it resulted positive in all patients at pre-operative setting. In particular, in pre-operative group, PET/CT showed an abnormal FDG-uptake in breast (n=84; 99%), in axillary lymph nodes (n=58; 68.2%), distant lymph nodes (n=20; 23.5%) and in distant organs (n=12; 14.1%). Conversely, four (5%) patients of post-operative subset had a positive PET/CT at breast level, five (6.3%) in axillary lymph nodes, 11 (13.8%) in distant lymph nodes and eight (10.5%) in distant organs. Stage grouping according to AJCC 7th edition was changed in 26/76 (34.2%) and 18/79 (22.8%) patients, respectively for pre and post-operative group (p=0.114). Moreover, the diagnostic accuracy in the post-operative setting for the detection of residual or distant metastases was: sensitivity: 100%; specificity: 71%, positive predictive value: 54%, negative predictive value: 100% and accuracy: 78.5%. Change in treatment was reported in 17 (10.3%) of patients, 4 in pre-operative and 13 in post-operative setting (5 vs. 16%, respectively; p=0.013). Conclusions: the decision to carry out an FDG PET/CT scan in initial evaluation of patients with locally advanced breast cancer should be probably taken in account. The change in staging is similar both in pre and post-operative setting, while the change in treatment is higher in post-operative subjects. A cost-effectiveness analysis seems necessary.