Human papillomavirus (HPV) related oropharyngeal cancers in Canada: A multicenter retrospective cohort study.

Oral human papillomavirus (HPV) infection is a risk for oropharyngeal cancer (OPC), now the leading HPV-related cancer in males in Canada. P16 positivity is a marker of HPV positivity. Since 2015, all major Canadian cancer centers perform routine p16 tumor marker testing of OPCs to define their HPV status but recent data on the HPV-attributable fraction for OPC in Canada do not exist. A retrospective chart review was conducted of all squamous cell OPC cases in patients 18 years and older diagnosed from 2016 to 2020 in 4 major Canadian hospital-based regional oncology centers to determine the HPV attributable fraction for OPC in Canada using p16 as a surrogate marker for HPV. 1154 OPC cases were identified. Most patients (85.4%) were male; about one-third 26 (31.4%) had never smoked. Most OPC (80.6%) were P16 positive. p16 positivity was 27 associated with younger age (mean age p16+ 61.6 vs. p16- 66.5 years,  < 0.0001), male sex 28 (p16+ males 84.0% vs p16+ females 60.9%, p < 0.0001), lower tumor stage (Stage 1 p16+ 29 88.1% vs Stage 4 p16+ 69.4%,  < 0.001), and non-smoking (never smoked 92.3% vs past 30 smoker 82.8% vs current smoker 65.0%,  < 0.001). Logistic regression confirmed these 31 associations. This study, the largest cohort of Canadian patients with OPC yet reported, demonstrates the high attributable fraction for HPV-related OPC. HPV-related OPC was more likely in men, younger individuals, and never smokers. These findings highlight the burden of HPV-related OPC in Canada and support gender-neutral HPV vaccination as an important public health strategy to prevent head and neck cancer.