Human papillomavirus positive squamous cell carcinoma of the oropharynx - A radiosensitive subgroup of head and neck carcinoma

BACKGROUND. Epidemiologic evidence points to a connection between viral inf ection by the human papillomavirus (HPV) and a subgroup of squamous cell ca rcinoma of the oropharynx. To assess the impact of HPV infection on the res ponse of these tumors toward radiotherapy, the authors retrospectively dete rmined the presence of the virus and the integrity of the viral E2 gene in tumors of patients who have undergone curative irradiation. METHODS. Paraffin embedded biopsies from 99 patients were analyzed for HPV infection and E2 gene integrity by multiplex PCR. The experimental findings were correlated with clinical characteristics, known risk factors, and tre atment outcome. RESULTS. Fourteen of 99 tumors were HPV positive (11 HPV16, 1 HPV33, 1 HPV3 5, and 1 HPV45). Human papillomavirus positivity was closely linked to fema le gender (odds ratio [OR], 5.75; P = 0.004), age older than 56 years (OR, 7.42; P = 0.012), nonsmokers (OR, 21.33; P = 0.00001), and alcohol abstaine rs (OR, 5.35; P = 0.012). There was en inverse association with p53 nuclear immunoreactivity (OR, 0.06; P = 0.008). The Kaplan-Meier survival estimate s showed a better local control (P = 0.050, log-rank) and a better overall survival (P = 0.046, log-rank) for patients with HPV positive tumors. In th e multivariate analysis, HPV positivity remained to be associated with a lo wer risk of local failure (risk ratio [RR], 0.31; P = 0.048). Four of 11 HP V16 positive tumors had a disrupted E2 gene. Only tumors with a disrupted E 2 gene manifested local treatment failure. CONCLUSIONS. Human papillomavirus positivity designates a specific subgroup of oropharyngeal squamous cell carcinomas of the oropharynx that arise pre ferentially among individuals with no consumption of tobacco and alcohol an d that have a favorable outcome attributable to an increased sensitivity to ward radiotherapy. (C) 2001 American Cancer Society.