Researchers have identified C5aR1 as a novel biomarker for metastasis risk and poor prognosis in patients with cutaneous squamous cell carcinoma (cSCC), the most common type of metastatic skin cancer. The new study’s findings in The American Journal of Pathology, published by Elsevier, found that C5aR1 promotes the invasion of cSCC tumor cells. Its elevated presence suggests that C5aR1 might serve as a useful prognostic marker for metastatic disease and, potentially, a target for future therapies in advanced cSCC.