Of 21 HR-HPV DNA-negative OPSCC patients, in 16 cases (76.2%), the HPV status of their tumor was not HPV-related (p16-), whereas five OPSCC patients (23.8%) had HPV-driven tumors, but their mouthwashes were not found to be positive for HPV despite each having a sufficient PCR control. This evidence concerns the gene CDKN2A and neoplasm.