Tengfei Li, Jintao Zhang, Yuanzhuo Yan, Yue Zhang, Wenjie Pei, Qingchu Hua, Yue Chen

Abstract:

Background: 68Ga-FAPI (fibroblast activation protein inhibitor) is a novel and highly promising radiotracer for PET/CT imaging. It has shown significant tumor uptake and high sensitivity in lesion detection across a range of cancer types. We aimed to compare the diagnostic value of 68Ga-FAPI and 18F-FDG PET/CT in common gynecological malignancies.

Methods: This retrospective study included 35 patients diagnosed with common gynecological tumors, including breast cancer, ovarian cancer, and cervical cancer. Among the 35 patients, 27 underwent PET/CT for the initial assessment of tumors, while 8 were assessed for recurrence detection. The median and range of tumor size and maximum standardized uptake values (SUVmax) were calculated.

Results: Thirty-five patients (median age, 57 years [interquartile range], 51-65 years) were evaluated. In treatment-naive patients (n = 27), 68Ga-FAPI PET/CT led to upstaging of the clinical TNM stage in five (19%) patients compared with 18F-FDG PET/CT. No significant difference in tracer uptake was observed between 18F-FDG and 68Ga-FAPI for primary lesions: breast cancer (7.2 vs. 4.9, P = 0.086), ovarian cancer (16.3 vs. 15.7, P = 0.345), and cervical cancer (18.3 vs. 17.1, P = 0.703). For involved lymph nodes, 68Ga-FAPI PET/CT demonstrated a higher SUVmax for breast cancer (9.9 vs. 6.1, P = 0.007) and cervical cancer (6.3 vs. 4.8, P = 0.048), while no significant difference was noted for ovarian cancer (7.0 vs. 5.9, P = 0.179). Furthermore, 68Ga-FAPI PET/CT demonstrated higher specificity and accuracy compared to 18F-FDG PET/CT for detecting metastatic lymph nodes (100% vs. 66%, P < 0.001; 94% vs. 80%, P < 0.001). In contrast, sensitivity did not differ significantly (97% vs. 86%, P = 0.125). For most distant metastases, 68Ga-FAPI exhibited a higher SUVmax than 18F-FDG in bone metastases (12.9 vs. 4.9, P = 0.036).

Conclusions: 68Ga-FAPI PET/CT demonstrated higher tracer uptake and was superior to 18F-FDG PET/CT in detecting primary and metastatic lesions in patients with common gynecological malignancies.