Exploring the Diagnostic and Theranostic Role of FAPI PET in Soft Tissue Sarcoma: A Systematic Review

Area of Science:

• Oncology
• Nuclear Medicine
• Radiochemistry

Background:

• Soft tissue sarcomas (STS) are a heterogeneous group of malignancies.
• Accurate diagnosis, staging, and treatment monitoring are crucial for STS management.
• Fibroblast activation protein (FAP) is overexpressed in many STS, making it a potential therapeutic target.

Purpose of the Study:

• To systematically review the diagnostic and theranostic applications of FAPI PET in STS.
• To compare the performance of FAPI PET/CT with FDG PET/CT in STS.
• To evaluate the efficacy and safety of FAPI-based radioligand therapy (RLT) in STS.

Main Methods:

• Systematic literature search of PubMed, Scopus, and Web of Science up to October 15, 2024.
• Inclusion of 36 studies involving 316 patients across approximately 30 STS subtypes.
• Synthesis of data on diagnostic accuracy, lesion detection, and therapeutic outcomes.

Main Results:

• FAPI PET/CT demonstrated superior tumor delineation and higher SUVmax/tumor-to-background ratios than FDG PET/CT, especially in vascular tumors.
• FAPI uptake metrics reliably correlated with FAP immunohistochemistry across various STS subtypes.
• FAPI PET/CT showed higher accuracy and better lesion detection for staging and restaging recurrent/metastatic STS.
• FAPI-based RLT resulted in disease stabilization in 16 out of 36 patients with a favorable safety profile.

Conclusions:

• FAPI PET/CT is a highly accurate imaging modality for diagnosing and monitoring soft tissue sarcomas, outperforming FDG PET/CT.
• FAPI-based radioligand therapy represents a promising and safe treatment strategy for challenging STS cases.
• Further research is warranted to optimize FAPI-based theranostics in STS management.