Symptom Clusters and Related Factors of Late Toxicities in Head and Neck Cancer Survivors After Radiation Therapy: A Cross-Sectional Study

<b>Background/Objectives</b>: Head and neck cancer survivors experience many late toxicities following radiation therapy. This study aims to identify symptom clusters of late toxicities and their related factors in head and neck cancer survivors. <b>Methods</b>: A cross-sectional study was conducted with 83 survivors (pharyngeal or laryngeal cancer) who had received radiation therapy at least one year earlier. Nine late toxicities were assessed using the Japanese version of the Patient Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) and a custom questionnaire. Quality of life (QoL) and related factors were evaluated with the European Organization for Research and Treatment of Cancer (EORTC QLQ-C 30), Hospital Anxiety and Depression Scale (HADS), UCLA Loneliness Scale, and Liebowitz Social Anxiety Scale (LSAS). Exploratory factor analyses and multiple regression analyses were performed. <b>Results</b>: All participants reported at least one symptom. Dry mouth (90.4%) and difficulty swallowing (72.3%) were particularly prevalent. Exploratory factor analysis (EFA) identified two symptom clusters (SCs): an oropharyngeal dysfunction cluster (pain, trismus, taste changes, difficulty swallowing, hoarseness) and a dry mouth cluster (dry mouth, sticky saliva). Regression analysis indicated that higher scores in both clusters were significantly associated with lower global QoL (oropharyngeal dysfunction SC: β = -0.427, <i>p</i> < 0.001; dry mouth SC: β = -0.268, <i>p</i> = 0.009). Chemoradiotherapy (CRT) was also significantly associated with higher cluster scores (oropharyngeal dysfunction SC: β = 0.233, <i>p</i> = 0.020; dry mouth SC: β = 0.343, <i>p</i> = 0.001). <b>Conclusions</b>: Late toxicities following radiation therapy include two clusters: oropharyngeal dysfunction cluster and dry mouth cluster. Head and neck cancer survivors with higher SC scores had lower global QoL scores and had undergone CRT. These findings may aid in the assessment and self-management support of head and neck cancer survivors after radiation therapy.