A total of 63.8 % of patients with oropharyngeal cancer ( 206 of 323 ) had HPV-positive tumors ; these patients had better 3-year rates of overall survival ( 82.4 % , vs. 57.1 % among patients with HPV-negative tumors ; P < 0.001 by the log-rank test ) and , after adjustment for age , race , tumor and nodal stage , tobacco exposure , and treatment assignment , had a 58 % reduction in the risk of death ( hazard ratio , 0.42 ; 95 % CI , 0.27 to 0.66 ) .
