Diagnostic capabilities of 68GA-FAPI PET/CT in gastric cancer

Abstract

Relevance: Gastric cancer remains a significant medical issue due to its high incidence and mortality rates. Hybrid imaging techniques, including positron emission tomography/computed tomography (PET/CT), play an important role in the diagnosis of malignant tumors, including gastric cancer. The development and clinical evaluation of radiopharmaceuticals used in oncology continues to advance.

The study aimed to evaluate the diagnostic capabilities of PET/CT using fibroblast activation protein inhibitor labeled with gallium-68 ([⁶⁸Ga]FAPI-PET/CT) in gastric cancer.

Methods: This review includes data from 8 clinical studies (both prospective and retrospective) comparing the diagnostic performance of [⁶⁸Ga]FAPI-PET/CT and fluorodeoxyglucose labeled with fluorine-18 ([¹⁸F]FDG) in patients with histologically confirmed gastric cancer. The number of patients in the studies ranged from 13 to 112, totaling 379 patients. The parameters analyzed included maximum standardized uptake value (SUVmax), tumor-to-background ratio (TBR), and the sensitivity in detecting primary gastric tumors, as well as lymph node and peritoneal metastases.

Results: According to multiple clinical studies, [⁶⁸Ga]FAPI demonstrated higher SUVmax and TBR values compared to [¹⁸F]FDG, especially in the visualization of diffuse, mucinous, and signet-ring cell histological subtypes of gastric cancer. This is associated with strong expression of FAP in the tumor stroma, enabling effective tracer accumulation in affected areas. Furthermore, [⁶⁸Ga]FAPI-PET/CT showed higher sensitivity in detecting primary gastric lesions (100% vs. 53%), lymph node metastases (79% vs. 54%), and peritoneal metastases (96% vs. 55%) compared to [¹⁸F]FDG-PET/CT. In 11–67% of patients, the use of [⁶⁸Ga]FAPI-PET/CT led to a change in tumor staging and influenced the formulation of an individualized treatment plan. 

Conclusion: [⁶⁸Ga]FAPI-PET/CT demonstrated greater diagnostic performance compared to [¹⁸F]FDG-PET/CT in staging gastric malignancies, particularly in histological subtypes with low glycolytic activity. The method offers superior sensitivity and visualization of peritoneal, visceral, and lymphatic metastases, playing a crucial role in determining treatment strategies.