Overall distribution of lymph node metastases
The frequency of LN metastases at each neck level is shown in Table 2. Overall, fifty-four of the sixty-three NDs were performed in cN+ve necks; of these, fifty-three were subsequently staged as pN+ve and one as pN0. The remaining nine NDs were performed in cN0 necks. Of these four (44%) were subsequently pN+ve, of which disease was invariably in Level II, and five remained pN0. This yielded an overall sensitivity of 93% and a specificity of 83% for cN0 staging in p16+ve OPSCC.