TP53 and head and neck squamous cell carcinoma: For example, the lack of statistical significance of N classification, HPV status, and TP53 mutation in the ten-variable multivariate analysis shown in Table 4 does not mean that they are irrelevant to outcome; each of these characteristics bears a significant univariate relation to outcome in HNSCC (Table 1), and their apparent lack of significance in the multivariate model might simply represent the difficulty in unraveling the individual contributions of multiple highly correlated variables, particularly with only 36 HPV-positive tumors.