The relevance of OPN as a marker of cancer aggressiveness has been reported in several malignancies, including breast, colorectal, pancreatic, lung, bladder, oral, head and neck cancer, and several other cancer types (Weber et al. 2010; Wisniewski et al. 2019; Petrik et al. 2006; Loosen et al. 2019). The gene discussed is SPP1; the disease is head and neck cancer.