Selective Neck Dissection - Rationale
For N+ oral cavity SCCA nodal mets would have remained in 50/246 patients at level IV and 10 of 246 at level V.
For N0 oropharyngeal and hypopharyngeal SCCA if level II - IV performed - no patient with hypopharyngeal and two with oropharyngeal would have had nodal mets remaining.