<h4>Background</h4>Like tumor cells, cancer-associated fibroblasts (CAFs) can enter the bloodstream and may function in systemic circulation.<h4>Methods</h4>Circulating CAFs (cCAFs) were isolated from the peripheral blood of head and neck squamous cell carcinoma (HNSCC) patients using CD45 depletion and detected by FAP expression using RT-qPCR. Here, FAP is linked to cancer.