Radiotherapy dose-volume parameters predict facial lymphedema after concurrent chemoradiation for nasopharyngeal carcinoma.

BACKGROUND: To investigate risk factors for developing radiation-associated facial lymphedema (FL) in nasopharyngeal carcinoma (NPC) patients after concurrent chemoradiation (CCRT).

METHODS: Clinical data from 87 patients who underwent definitive CCRT for NPC in 2010-2018 was retrospectively evaluated. FL severity was graded using MD Anderson Cancer Center head and neck lymphedema rating scale. Logistic regression analysis was used to examine the factors associated with the presence of moderate/severe FL (grade ≥ 2).

RESULTS: At a median follow-up of 34 months (range, 18-96), 26/87 (29.9%) patients experienced grade ≥ 2 FL. A majority (84.6%) was experienced grade ≥ 2 FL 3-6 months after CCRT. Mean dose to the level IV, level I-VII neck node and N stage were significantly correlated with grade ≥ 2 FL at univariate analysis. At multivariate analysis, mean dose of level IV neck node (hazard ratio [HR], 1.238; 95% confidence interval [CI] = 1.084-1.414; p = 0.002) and level I-VII neck node (HR, 1.384; 95% CI = 1.121-1.708; p = 0.003) were independent predictors. Receiver Operating Characteristics (ROC) curve analysis showed that cut-off value of mean level IV neck node dose was 58.7 Gy (area under the curve [AUC] = 0.726; 95% CI = 0.614-0.839, p = 0.001) and mean level I-VII neck node dose was 58.6 Gy (AUC = 0.720; 95% CI = 0.614-0.826, p = 0.001) for grade ≥ 2 FL.

CONCLUSIONS: Keeping mean dose to the level IV and level I-VII below 58.7 Gy and 58.6 Gy may reduce the likelihood of moderate/severe FL after CCRT for NPC.