Reviewer #2: The authors wrote a ni

Reviewer #2: The authors wrote a nice manuscript about the distribution of cervical lymph node metastasis in NPC patients. In addition the propose an alternative upper edge of level IIb for selected patients.I have some minor comments:1. It would be nice if the authors would have added a figure where it becomes more clear what is the difference in delineation of level IIb in the modified and control group.2. How is local control defined. Is this including regional control. The addition of regional control should be added. In the discussion section (page 16, lines 48-54) the authors added new information that no marginal or out-of-field recurrences were seen in the optimized contouring method. This should be added in the results section. And how is this for the control group?3. How do the authors came up with the inclusion criteria in de modified group,? Is this based on literature? If yes, please add this information. And discus these criteria in the discussion section.Some other comments:1. Page 8, line 45-51. Add literature references.2. Table 2 is not clear. Please add the definition of LNc2 and LNab in the legend of the table.3. The quality of figure 1 is very bad. This should be modified or omitted.