The F18 FDG PET in breast carcinoma: Do patient characteristics, tumor histology or receptor status, have any impact on final staging?

Background: The F18-FDG PET CT has been shown to have a large impact on staging and subsequent management of various oncologic patient populations. Several reports have shown greater benefits with F18-FDG PET CT scan over conventional imaging modalities (diagnostic CT scan and nuclear bone scan) with clinical upstaging rates exceeding 30% which certainly leads to significant changes in management and subsequent treatment plans. Breast cancer is one of several indications where F18-FDG PET CT has shown greater sensitivity compared to conventional imaging in detecting regional and distant metastases. However, little is described about the characteristics and oncologic profile for those experiencing clinical upstaging following on F18-FDG PET CT. Thus, we aim to describe our experience with F18-FDG PET/CT in breast cancer patients and evaluate the characteristics of those who experienced clinical stage modification.

Methods: A retrospective review approved by our Institutional Review Board was carried out. We included all adult female patients diagnosed with breast cancer at our institution and underwent F18-FDG PET CT between January 1st, 2014 and December 31st, 2018 prior to any treatment. Patients’ characteristics including staging and management modification were described before and after F18-FDG PET CT. Continuous variables expressed as median (Interquartile ranges) and categorical as proportions.

Results: A total of 283 patients were included in the study. There were 97 patients (34.3%) who were clinically upstaged including 31 patients upstaged to stage IV, 40 to stage IIIC, 15 to stage IIIA, and 11 to stage IIB. There was no statistical difference in age or tumor histology type between patients who were upstaged compared to those who were not. However, in the group of patients who were upstaged, there were more patients with triple negative receptor status compared to those who were not upstaged (45% vs. 27% p&lt0.05).

Conclusions: For staging purposes patients' characteristics and tumor histology type did not appear to impact final staging. Patients with triple negative receptor status were frequently upstaged on F18-FDG PET CT. Whether this is an independent factor for changes in staging on F18-FDG PET CT requires validation with a larger patient population.