Tumor factors associated with in-field failure for nasopharyngeal carcinoma after intensity-modulated radiotherapy.

Abstract

To identify the tumor factors of in-field failure for nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era. Patterns of recurrence were classified as in-field, marginal, and out-field failures. Multivariate analyses with the Cox proportional hazards model were used to identify tumor-related factors of in-field failure. A total of 1039 patients with NPC received IMRT from 2012 to 2019 and 75 developed recurrences, with 88.0% (66/75) considered as having in-field failures. Multivariate analysis showed that pretreatment gross tumor volume of nasopharynx ≥68.8 mL and histopathological type of nonkeratinizing differentiated carcinoma (NKDC) were the independent tumor factors of in-field local failure, while gross tumor volume of involved lymph nodes ≥19.9 mL and cervical nodal necrosis (CNN) were associated with in-field regional failure (all p < 0.05). In-field failure was the major pattern of recurrence in patients with NPC. Large tumor volume, NKDC, and CNN were the tumor factors associated with in-field failure.