Current guidelines do not systematically recommend 18F-FDG PET/CT for breast cancer staging; and the recommendations and level of evidence supporting its use in different groups of patients vary among guidelines. This review summarizes the evidence about the role of 18F-FDG PET/CT in breast cancer staging and the therapeutic and prognostic impact accumulated in the last decade. Other related aspects, such as the association of metabolic information with biology and prognosis are considered and evidence-based recommendations for the use of 18F-FDG PET/CT in breast cancer staging are offered. We systematically searched MEDLINE for articles reporting studies with at least 30 patients related to clinical questions following the Problem/Population, Intervention, Comparison, and Outcome framework. We critically reviewed the selected articles and elaborated evidence tables structuring the summarized information into methodology, results, and limitations. The level of evidence and the grades of recommendation for the use of 18F-FDG PET/CT in different contexts are summarized. Level III evidence supports the use of 18F-FDG PET/CT for initial staging in patients with recently diagnosed breast cancer; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a weak recommendation in this population. In patients with locally advanced breast cancer, level II evidence supports the use of 18F-FDG PET/CT for initial staging; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a strong recommendation in this population. In patients with recently diagnosed breast cancer, the metabolic information from baseline 18F-FDG PET/CT is associated with tumor biology and has prognostic implications, supported by level II evidence. In conclusion, 18F-FDG PET/CT is not recommended for staging all patients with early breast cancer, although evidence of improved regional and systemic staging supports its use in locally advanced breast cancer. Baseline tumor glycolytic activity is associated with tumor biology and prognosis.

To analyze the correlation between [(18)F]-fluoro-2-deoxy-D-glucose (F-FDG) uptake assessed by positron emission tomography/computed tomography (PET/CT) in breast tumors and histopathologic and immunohistochemical prognostic factors. Sixty-eight women with breast cancer were prospectively evaluated. PET/CT was requested in the initial staging previous to neoadjuvant chemotherapy (multicentric study).All the patients underwent a standard (18)F-FDG PET/CT followed by a delayed acquisition, 1 hour (PET-1) and 3 hours (PET-2) after FDG administration. Both examinations were evaluated qualitatively and semiquantitatively (SUV(max) values) in PET-1 (SUV-1) and in PET-2 (SUV-2). The percentage variation of the standard uptake values (retention index) between PET-1 and PET-2 was calculated.Clinical and metabolic stages were assessed according to TNM classification. All biologic prognostic parameters, such as the receptor status, p53 and c-erbB-2 expression, proliferation rate (Ki-67), and grading were determined from tissue of the primary tumor. Metabolic, clinical, and biologic parameters were correlated. A positive relationship was found between the SUV(max), tumor size, clinical, and metabolic stages. SUV-1 and SUV-2 values showed significant statistical correlation (P < 0.05) with PET stage and tumor size assessed by PET. On the contrary, the retention index showed relation with clinical stage (P < 0.05).When related to the biologic parameters, retention index showed the best results, with positive and significant relation (P < 0.05), with histologic grade, and Ki-67 and c-erbB-2 expression. Isolated SUV values only showed significant relation to Ki-67 expression. The retention index showed the best relation with biologic and clinical parameters compared with isolated SUVmax values for what could be a predictive marker of tumor biologic behavior.