Comparison of ⁶⁸ga fapi pet/ct and ¹⁸f-fdg pet/ct in primary staging of breast cancer.

Abstract

PurposeTo evaluate the role of ⁶⁸Ga-FAPI PET/CT in primary staging of breast cancer in comparison with ¹⁸F-FDG PET/CT.MethodsIn this prospective study, 50 breast cancer patients (49F,1M, age:54.56 ± 13.73) were included. ¹⁸F-FDG PET/CT and ⁶⁸Ga-FAPI PET/CT were performed consecutively for staging purposes. Patient-based sensitivity, specificity, PPV, NPV and accuracy were calculated. Relationship between semiquantitative ⁶⁸Ga-FAPI PET parameters and histopathology were analysed.ResultsPatient based sensitivity for detection of primary breast lesions of ⁶⁸Ga-FAPI were higher than ¹⁸F-FDG PET/CT (100 % (95 % CI: 92.9-100.0) vs 92 % (95 % CI: 80.4-100)), although not reached statistical significance (exact McNemar p = 0.0625). PPV was 100 % (95 % CI: 92.9-100.0) for both modalities. For lymph node metastases, patient-based sensitivity, specificity, PPV, NPV and accuracy of 68 Ga-FAPI PET/CT were 72.4 % (95 % CI: 52.8-87.3), 95.2 % (95 % CI: 76.2-99.9), 95.5 % (95 % CI: 77.2-99.9), 71.4 % (95 % CI: 51.3-86.8) and 82.0 % (95 % CI: 68.6-91.4), respectively, whereas those of ¹⁸F-FDG PET/CT were 60.7 % (95 % CI: 40.6-78.5), 85.7 % (95 % CI: 63.7-97.0), 85.0 % (95 % CI: 62.1-96.8), 62.1 % (95 % CI: 42.3-79.3) and 71.4 % (95 % CI: 56.7-83.4), respectively (for sensitivity and specificity, exact McNemar p = 0.125 and p = 0.50). Mean SUVmax of ⁶⁸Ga FAPI uptake of primary breast lesions were significantly higher than ¹⁸F-FDG uptake (13.32 ± 7.1 vs 6.86 ± 3.51p Conclusion⁶⁸Ga-FAPI PET/CT demonstrated promising diagnostic performance for the detection of primary breast tumors, lymph node metastases, and selected distant metastatic lesions. Although paired statistical analysis did not demonstrate significant differences compared with ¹⁸F-FDG PET/CT, ⁶⁸Ga-FAPI PET/CT provided additional clinically relevant findings in a subset of patients. Larger multicenter studies are needed to further define its clinical role in breast cancer staging.