[18F]FDG PET/CT as a biomarker for response evaluation in neoadjuvant treatment of early breast cancer: could it become a game-changer in the scenario of the emerging (de)-escalation strategies?

Over the past decades, neoadjuvant systemic treatment (NAT) has been increasingly adopted in early-stage breast cancer (BC), highlighting the need for a more accurate assessment of treatment response. Imaging tools such as [¹⁸F]2-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) positron emission tomography combined with computed tomography (PET/CT) may enhance diagnostic accuracy in this context. By comprehensively reviewing the available literature, [¹⁸F]FDG PET/CT generally shows good sensibility but lower specificity for predicting and evaluating pathological complete response (pCR), respectively, during NAT and preoperatively, in both the breast and lymph nodes. Thereby its use may support timely escalation of systemic treatment or surgery in patients with poor metabolic response. However, definitive conclusions are limited by small, heterogeneous studies with variable patient selection, timing, and response definitions. Consequently, while international guidelines remain inconsistent, further evidence is needed to define its role in response assessment, establish the optimal use in clinical practice, and clarify its integration into (de)-escalation strategies.