Diagnostic value of [68Ga]Ga-FAPI-46 PET in comparison to [18F]FDG PET in triple-negative breast cancer and potential for theranostic application.

This single-center subgroup analysis of a prospective trial (NCT04571086) at University Hospital Essen investigated tumor uptake and detection rates of [68Ga]Ga-FAPI-46- versus [18F]FDG PET in triple-negative breast cancer (TNBC) patients undergoing initial or follow-up staging. Lesions were recorded across anatomical regions, with detection efficacy, uptake values, tumor-to-liver ratios, and tumor volumes assessed. 22 patients were included (initial- n = 10, follow-up staging n = 12). No significant difference in region-based detection rates was observed between [18F]FDG- (93%, 53/57 regions) and [68Ga]Ga-FAPI-46 PET (93%, 53/57 regions) (McNemar p = 1.0). Three patients (25%) at follow-up staging showed an average tumor SUVmean ≥5 on [68Ga]Ga-FAPI-46 PET; 2/3 showed SUVmax >10 in most lesions. Mean tumor volume was higher for [68Ga]Ga-FAPI-46, though not statistically significant at initial- (50.1 ± 120.8 mL vs. 11.9 ± 18.5 mL) and follow-up staging (102.2 ± 122.3 mL vs. 79.0 ± 90.4 mL). [⁶⁸Ga]Ga-FAPI-46 PET demonstrated comparable detection in TNBC; high tumor uptake in a subset, supporting its theranostic potential.