The analyses of overall survival were not able to identify any significant associations with the hypermethylation status of the five investigated genes in the HNSCC cases (Table 4), but, given the association between CCNA1 and TIMP3 hypermethylation and the development of SPT, the second primary tumor-free survival at 3-years was also evaluated (Table 4). Here, CCNA1 is linked to head and neck squamous cell carcinoma.