FDG-PET Outperforms CT in Assessing Treatment Response for Metastatic Breast Cancer

A recent study published in the European Journal of Radiology suggests that fluorodeoxyglucose-positron emission tomography (FDG-PET) is more effective than computed tomography (CT) in evaluating treatment response for patients with metastatic breast cancer. Conducted on a cohort of 51 women who received systemic treatment for their condition, the comparative analysis found notable differences in the performance of these imaging modalities.

The researchers assessed 375 scans, including 151 paired sets of FDG-PET and CT scans conducted between 2017 and 2025. The study applied PERCIST criteria to FDG-PET scans and RECIST 1.1 criteria to CT scans. Findings revealed that all FDG-PET scans identified measurable target lesions, while only 35 percent of the CT scans did so.

Lead author Dr. Vilma Landfors Andersson of Lund University in Sweden highlighted a significant limitation of the CT-based RECIST 1.1 criteria. In 65 percent of the CT scan pairs, no measurable target lesions were found, a discrepancy mainly attributed to bone-only disease or lymph nodes falling below the threshold size required for detection by the criteria. In contrast, FDG-PET detected measurable target lesions in all 151 pairs.

In instances where both imaging modalities identified measurable lesions, there was a 79 percent agreement on the location of these lesions. However, the overall concordance for target-lesion identification dropped to 28 percent across all scan pairs. This discrepancy raises concerns over the consistency and reliability of CT scans for lesion tracking.

Moreover, the study found that FDG-PET flagged disease progression a median of 50 days earlier than CT. In 61 percent of cases, FDG-PET detected progression sooner, while CT did not outperform FDG-PET in any instance. These results suggest that FDG-PET might offer more timely treatment evaluations and could play a significant role in clinical trial patient selection.

The authors note the potential implications of these findings, particularly regarding the limitations of CT-based criteria for clinical trials and the benefits of incorporating FDG-PET for improved treatment assessments. The study, despite its non-randomized retrospective nature and small cohort size, provides crucial insights into the effectiveness of FDG-PET versus CT in the context of metastatic breast cancer imaging.