CDKN2A and oropharynx cancer: A Canadian retrospective study of 406 oropharyngeal cancer patients reported a significantly lower incidence rate of SPTs in those who were p16-positive, which is indicative of HPV-related oropharyngeal cancer patients (0.7 per 100 patient-years vs. 8.5 in p16-negative patients, p < 0.0001) (40).