Patients
tumor, malignancy, TD, HNSCC, Cancer
REGRESSION, TUMOR, NASOPHARYNGEAL CANCER, CANCER
We conducted an observational, retrospective, non‐randomized study after obtaining approval from the ethics committee of Donostia University Hospital (AVV‐EDC‐2017‐01) on patients with HNSCC staged according to the 8th Edition criteria of the AJCC. We selected patients aged 18 years or older who underwent initial surgery with neck dissection (ND) followed by adjuvant radiotherapy (RT) ± chemotherapy (CTX) between 2012 and 2018, while excluding those with previous ND, RT, or chemoradiation (CTX‐RT). Moreover, patients with synchronous malignancy, nasopharyngeal cancer, less than 3 years of follow‐up, HNSCC of unknown primary and non‐squamous cell histologies were also excluded. Adjuvant treatment was indicated according to the National Comprehensive Cancer Network (NCCN) guidelines.We used IBM SPSS v26 software for statistical analysis. The Kolmogorov–Smirnov and Shapiro–Wilk tests were performed to evaluate the absence of normal data distribution, and nonparametric tests were used. The Mann–Whitney U test and Kruskal‐Wallis 1‐way ANOVA tests examined the differences in medians among groups for two samples and more than two samples, respectively. In order to investigate the relationship between variables in the various groups, we employed a Multinomial logistic regression test and calculated the Likelihood Ratio (LRT). Prior to this analysis, to ensure the validity of our results we assessed multicollinearity for each predictor variable by calculating variance inflation factor (VIF) values using a linear logistic regression (independent variables if VIF = 1; variables moderately correlated if VIF 1 < VIF <5; multicollinearity among the predictors if VIF ≥5 to 10).Survival was calculated by the Kaplan–Meier method, and the log‐rank test was employed to compare survival curves. A univariate Cox regression analysis using the enter method was conducted, evaluating the correlation between OS and clinical factors, including gender, age, tumor location, T category, systemic treatment, local‐regional progression and the presence of ENE or TDs. A multivariate Cox regression analysis using the enter method was performed to simultaneously assess the effect of the risk factors on OS and to estimate the corresponding hazard ratios (HRs). Additionally, since including patients with both ENE and TD simultaneously could be considered a confounding factor, we performed a sensitivity analysis by excluding patients who had both ENE and TDs. After removing these patients, we repeated all the statistical tests to ensure the robustness of our results. In all cases, a statistically significant test result was considered as 