Human papillomavirus and survival in patients with base of tongue cancer

The incidence of base of tongue cancer is increasing in Sweden and the proportion of human papillomavirus (HPV) positive cancer has increased in Stockholm, Sweden. Between 2006 and 2007, 84% of base of tongue cancer cases in Stockholm were HPV-positive. The objective of this study was to assess the impact of HPV status on prognosis for base of tongue cancer patients. One-hundred and nine patients were diagnosed with base of tongue cancer between 1998 and 2007 in Stockholm County and 95 paraffin-embedded diagnostic tumor biopsies were obtained and tested for HPV by PCR. Eighty-seven patients had available biopsies, were treated with intention to cure and could be included in the survival analysis. Age, sex, TNM-stage, stage, treatment and survival were recorded from patient charts. Kaplan-Meier curves were used to present survival data. In multivariable analyses, a Cox proportional hazards model was used to adjust for covariates. In total 68 (78%) tumor biopsies from the 87 included patients were HPV DNA positive. Kaplan-Meier estimates showed that the overall survival for patients with HPV-positive cancer was significantly better (p = 0.0004), (log-rank test) than that of patients with HPV-negative cancer. Patients with HPV-positive tumors also had significantly better disease-free survival (p = 0.0008), (log-rank test) than those with HPV-negative tumors. These results further strengthen the option to consider HPV-status when planning prospective studies on treatment for base of tongue cancer.