GPR18 and head and neck squamous cell carcinoma: After selecting genes with HR > 1, which also maintained an association with OS in a validation cohort dataset (GSE65858) and were not related to disease stage or alcohol history as confounders (when using a multivariate proportional hazard Cox model), six genes including FABP4, GDNF, HMGA2, S100A10, SLC7A2, and GPR18, were found to be significantly associated with clinical outcomes exclusively in HPV-positive HNSCC patients (Table 1).