Reducing Dose and Irradiated Volume in Cervical Prophylactic Irradiation for Nasopharyngeal Cancer

For N0 disease, only cover bilateral RPN and level II. For N1 disease, cover ipsilateral involved level plus subsequent level downword, and cover contralateral level RPN and level II. For N2 disease, cover ipsilateral involved level plus subsequent level downword. For N3 disease, cover ipsilateral involved level plus subsequent level downword, and ensuring a 2cm margin below GTVn if GTVn reach or near the sternoclavicular joint. Notably, for unilateral N3, the contralateral neck would only include RPN and level II. Prescribing dose for CTVn2 was 50Gy/33Fx.