Exploring the Application Value of PET Molecular Imaging Targeting FAP in Oral Squamous Cell Carcinoma

Positron emission tomography (PET) molecular imaging provides a valuable method for the diagnosis, differential diagnosis and staging of various tumors. Cancer associated fibroblasts (CAFs) are the main components of tumor stroma, which are involved in tumor cell proliferation, invasion, metastasis and tumor angiogenesis, and play an important role in the occurrence and development of tumors. Fibroblast activation protein (FAP) is the most potential specific molecular marker of CAF, which is mainly expressed in stromal fibroblasts of epithelial tumors and is a potential molecular target for tumor diagnosis and treatment. Oral cancer is the most common type of malignant head and neck cancer, seriously endangering human health. Accurate delineation of the primary tumor, detection of regional nodal metastases, distant metastases and second primary tumors are important for determining the therapeutic strategy and prognosis of oral cancer. Currently, the molecular imaging agent most commonly used in clinical practice for oral cancer is 18F-fluoro-deoxy-glucose (18F-FDG). However, 18F-FDG exhibits some shortages. Inflammatory lesions and the surrounding normal tissue such as brain, tonsils and salivary glands show high uptake of 18F-FDG, often affecting the judgment of lesions. Adult patients aged \>18 years with clinically confirmed or highly suspected oral cancer will be enrolled. Participants receive paired baseline FDG and FAPI PET/CT to explore the diagnostic and staging value of FAPI PET in oral cancer. For resectable locally advanced cases receiving neoadjuvant therapy from oral and maxillofacial clinicians, a follow-up FAPI PET imaging will be performed after two cycles of treatment and before surgery to evaluate its application in treatment-response assessment. Ultimately, this study aims to comprehensively evaluate the clinical utility of FAPI PET/CT in oral cancer.