SPP1 and head and neck squamous cell carcinoma: SPP1+ macrophages have been identified in a variety of human cancers through single-cell RNA sequencing and spatial transcriptomics studies such as colorectal cancer (CRC) (10, 16, 19), lung cancer (LC) (12, 20), breast cancer (BC) (21, 22), non-small cell lung cancer (NSCLC) (20, 23), hepatocellular carcinoma (HCC) (18), ovarian cancer (24), head and neck squamous cell carcinoma (HNSCC) (25) and anaplastic thyroid cancer (ATC) (26) & pancreatic ductal adenocarcinoma (PDAC) (27, 28).