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PRISMA diagrams for selection of (A) interventional studies and (B) non‐interventional studies. HN, head and neck; HNC, head and neck cancer; HPV, human papilloma virus; n, number of studies; OPC, oropharyngeal cancer; OPX, oropharynx. †Number of excluded articles per reason does not add up to total number of excluded articles as many cases were excluded for more than one reason.
