Abstract
Abstract
Accurate pathological response assessment of breast cancer following neoadjuvant therapy (NAT) is clinically critical but lacks robust imaging methods, so this study evaluated the diagnostic accuracy of
18
F-fluorodeoxyglucose (FDG) PET/CT and
68
Ga-fibroblast activation protein inhibitor (FAPI) PET/CT in clinically node positive (cN+) breast cancer patients receiving NAT. This prospective study enrolled pathologically confirmed breast cancer patients who underwent NAT and both PET/CT scans preoperatively. The maximum standardized uptake value (SUVmax) was measured and an optimal
68
Ga-FAPI PET/CT threshold was determined via receiver operating characteristic (ROC) curve analysis. Among 75 patients, 33 (44.0%) achieved pathological complete response (pCR). SUVmax was significantly lower in the ypT0/Tis group compared to the ypT+ group for both
18
F-FDG PET/CT (1.45 ± 0.55 vs. 5.19 ± 4.69,
p
68
Ga-FAPI PET/CT (1.59 ± 1.22 vs. 10.45 ± 8.54,
p
68
Ga-FAPI PET/CT demonstrated higher sensitivity in detecting residual disease compared to
18
F-FDG PET/CT (0.8 vs. 0.6,
p
= 0.003), with comparable specificity (0.9 vs. 0.9,
p
= 1.00). Exploratory subgroup analysis found that
68
Ga-FAPI PET/CT had superior sensitivity compared to
18
F-FDG PET/CT in the hormone receptor-positive (HR + ) group (0.8 vs. 0.6,
p
= 0.02). These findings show that
68
Ga-FAPI PET/CT outperforms
18
F-FDG PET/CT in identifying residual breast lesions after NAT in cN+ patients, particularly among HR+ patients, which would guide further treatment strategies after NAT.