Fapi Pet-ct in Detecting Minimal Residual Disease and Subclinical Metastatic Sites in Post-treatment Breast Cancer

Background Breast cancer has become the most common type of cancer, surpassing lung cancer, and is the leading cause of cancer-related deaths among women worldwide. Ga-68 FAPI PET-CT has currently evolved in multiple aspects in breast cancer assisting in diagnosis, initial staging, re-staging, suspected recurrence, and evaluating therapeutic response. It has also shown a role in other malignancies like sarcoma, esophageal cancer, cholangiocarcinoma, and lung cancer. Methods A retrospective analysis of Ga-68 FAPI PET-CT scans of forty-five patients aged eighteen and older with confirmed breast cancer who have undergone various treatments (surgery, chemotherapy, radiotherapy) was performed. The role Ga-68 FAPI PET–CT imaging in the detection of minimal residual disease and subclinical metastatic sites in breast cancer patients after initial treatment was analyzed. Results A total of 45 patients with histologically confirmed breast cancer and post treatment underwent Ga-68 FAPI PET-CT and Conventional CT and /or MRI. Ga-68 FAPI PET-CT showed 100% sensitivity and 82.5% specificity in detecting minimal residual disease, significantly outperforming conventional imaging, which identified lesions in only 11.1% of patients compared to 26.7% with PET-CT. Notably, Ga-68 FAPI PET-CT was better at detecting liver metastases (15.6% vs. 6.7%) and axillary metastases (11.1% vs. 4.4%). All patients with residual primary disease detected by Ga-68 FAPI PET-CT experienced recurrence (100%). However, those without residual primary disease, only 9.1% experienced recurrence. Recurrence-free survival was significantly longer in patients without residual disease (58.6 vs. 12.4 months, P < 0.001). Conclusion Ga-68 FAPI PET-CT has shown to be a probably sensitive and specific imaging modality that can effectively detect minimal residual disease and subclinical metastases in breast cancer patients. This study may potentially help in earlier detection of breast cancer recurrences hence timely interventions and improved patient outcomes.