Human papillomavirus infection predicts a better survival rate in patients with oropharyngeal cancer

Introduction: Squamous cell carcinoma is the most common malignant tumour occurring in the head and neck region. It is now understood that (human papillomavirus (HPV)- positive and HPV-negative diseases are two very different clinical entities associated with different outcomes. We decided to assess p16 expression status in patients with oropharyngeal cancer and retrospectively evaluate the outcomes of the treatment. Material and methods: The evaluated group consisted of 98 consecutive patients with squamous cell carcinoma of the oropharynx treated in a combined way in Holycross Cancer Centre in Kielce in 2006-2014. For all patients p16 status was assessed based on the biological material. In 51 patients HPV infection was diagnosed. The Kaplan-Meier method was used to produce survival curves using the log-rank test and the Cox proportional hazard model was used to determine the risk factors. The following risk factors were included: HPV status (positive, negative), sex, age, smoking, histopathological grade of the tumour, clinical stage, and systemic therapy application. For HPV-positive and HPV-negative patients independent analyses were done including aforementioned factors, excluding HPV status. Results: The observation time for HPV-positive patients was significantly longer (p = 0.0008). Fifty-eight patients died, 40 patients are alive. Number of deaths in HPV-negative patients was statistically significantly higher (p = 0.0222). A statistically significant difference in the disease-free survival probability and overall survival probability between HPV-positive and HPV-negative patients was found (p = 0.0045 and p = 0.0037 respectively). For disease-free survival a statistically significant factor of the risk of recurrence was HPV infection (p = 0.0169). For HPV-positive patients, age (p = 0.0199) and smoking (p = 0.0353) were statistically significant risk factors of recurrence. For HPV-negative patients significant risk factors of recurrence were clinical stage (p = 0.0114) and systemic therapy application (p = 0.0271). For overall survival for the entire group statistically significant risk factors were absence of HPV infection (p = 0.0123), male sex (p = 0.0426), and age (p = 0.0311). For HPV-positive patients, age (p = 0.0096) and smoking (p = 0.0387) were statistically significant risk factors of death. For HPV-negative patients significant risk factors of death were clinical stage (p = 0.0120) and systemic therapy application (p = 0.0460). Conclusions: Our data show that HPV infection is a predictor of better disease-free and overall survival in patients with oropharyngeal cancer. For HPV-positive oropharyngeal cancer patients weekly given cisplatin with concurrent radiotherapy can be an alternative to three weekly given cisplatin considering effectiveness and early toxicity.