Low hemoglobin levels predict increased radiation-induced trismus rates in nasopharyngeal cancer.

Abstract

To investigate the predictive significance of hemoglobin (Hb) values in the incidence of radiation-induced trismus (RIT) in locally advanced nasopharyngeal carcinoma (LA-NPC) patients who received concurrent chemoradiotherapy (C-CRT). Data of LA-NPC patients were examined before and after C-CRT and to confirm the presence of RIT, maximum mouth openings (MMO) were measured; RIT is defined as an MMO of ≤35 mm. All Hb values were derived from complete blood count tests obtained on the first day of C-CRT. The receiver operating characteristic (ROC) curve analysis was used to scrutinize a possible connection between pre-treatment Hb values and RIT status. Two hundred and twenty three patients were included in the study and RIT was diagnosed in 46 (20.6%) patients. The Hb cutoff in ROC curve analysis that separated the patients into two groups was 12.05 g/dL [Area under the curve (AUC): 82.7%; sensitivity: 72.9%; and specificity: 71.3%]. RIT was significantly more prevalent in the Hb ≤ 12 g/dL group than in its counterpart (41.9% vs. 7.3%; p < 0.001). In multivariate analysis, Hb ≤ 12, anemia, pre-C-CRT MMO < 41.4 mm, and masticatory apparatus doseV58 Gy < 32% groups were found to be independently associated with significantly increased rates of RIT. Low pre-C-CRT Hb and anemia status are novel biological markers that independently predict higher RIT rates in LA-NPC undergoing C-CRT.