Reduced-Volume Irradiation of Uninvolved Neck in Patients With Nasopharyngeal Cancer: Updated Results From an Open-Label, Noninferiority, Multicenter, Randomized Phase III Trial.

JCO We previously reported comparable 3-year regional relapse-free survival (RRFS) using elective upper-neck irradiation (UNI) in N0-1 nasopharyngeal carcinoma (NPC) compared with standard whole-neck irradiation (WNI). Here, we present the prespecified 5-year overall survival (OS), RRFS, late toxicity, and additional analyses. In this randomized trial, patients received UNI (n = 224) or WNI (n = 222) for an uninvolved neck. After a median follow-up of 74 months, the UNI and WNI groups had similar 5-year OS (95.9% 93.1%, hazard ratio [HR], 0.63 [95% CI, 0.30 to 1.35]; = .24) and RRFS (95.0% 94.9%, HR, 0.96 [95% CI, 0.43 to 2.13]; = .91) rates. The 5-year disease-free survivors in the UNI group had a lower frequency of hypothyroidism (34% 48%; = .004), neck tissue damage (29% 46%; < .001), dysphagia (14% 27%; = .002), and lower-neck common carotid artery stenosis (15% 26%; = .043). The UNI group had higher postradiotherapy circulating lymphocyte counts than the WNI group (median: 400 cells/μL 335 cells/μL, = .007). In conclusion, these updated data confirmed that UNI of the uninvolved neck is a standard of care in N0-1 NPC, providing outstanding efficacy and reduced long-term toxicity, and might retain more immune function.