Optimizing cervical target volume in patients with nasopharyngeal cancer based on nodal drainage distance.

In NPC, the maximum LN drainage distance was 3.95 cm without considering the direction. Specifically, in cranial-to-caudal direction, the sufficient vertical drainage distance was 2.81 cm, indicating that a 3-cm extension from the most inferior node may be rational as caudal border of the prophylactic clinical target volume (CTV). These findings promote in-depth understanding of nodal spreading patterns, uncovering paramount evidence for individualized CTV.