Risk of second primary neoplasia in patients with oropharyngeal carcinoma: Role of HPV status in the outcome.

Abstract

e17544 Background: Patients with HPV-positive oropharyngeal cancer (OPC) have better prognosis and a lower risk of appearance of second primary neoplasm (SPN) than HPV-negative OPC patients. The aim of our study was to analyze the risk of developing SPN in a large group of patients with OPC according to HPV status in the primary tumor and its relationship with toxic habits. Methods: This study includes patients from a prospective data-base: 484 OPC patients were treated from 1991 to 2017 for which the HPV DNA positivity was evaluated by PCR in available tumor specimens. HPV DNA positive samples were further tested for HPV E6*I mRNA detection and/or p16INK4a immunohistochemistry. The mean follow-up of patients included in the study was 4.9 years (SD 5.1 years). We estimated the incidence of SPN in all cancer sites and in cancer sites related to tobacco and alcohol consumption according to the HPV status in the primary tumor. Results: Ninety-nine (20.5%) out of 484 OPCs included in the study were HPV-related. During the follow-up period, 127 patients with HPV-negative tumors (33.0%) and 19 patients with HPV-positive tumors (19.2%) had a SPN. Considering only the tobacco/alcohol-related SPNs, 106 of the patients with HPV-negative tumors (27.5%), and 12 patients with HPV-positive tumors (12.1%) had a tobacco/alcohol-related SPN (P < 0.0001). Five-year and 10-year SPN-free survival for HPV-negative versus HPV-positive OPC patients was 61.0% versus 81.5%, and 37.6% versus 73.8%, respectively (P < 0.001). When restricting the analyses to tobacco/alcohol-related SPNs, the corresponding survival rates were 66.6% versus 86.8% and 45.9% versus 83.5% for 5-year and 10-year survival rates, respectively (P < 0.0001). The frequency of tobacco/alcohol-related SPNs occurrence throughout the follow-up period for patients with HPV-negative OPC was 27.5%, for patients with HPV-positive tumors with a previous history of severe tobacco and/or alcohol use was 21.4%, and for patients with HPV-positive tumors without a history of severe tobacco and/or alcohol consumption it was 8.5% (P < 0.0001). Conclusions: HPV status and previous toxic habits might allow classifying patients regarding the risk of tobacco/alcohol-related SPNs. HPV-related OPC patients without previous history of severe tobacco and/or alcohol use have a significant low risk of SPN development, particularly in those locations related to tobacco use or alcohol consumption