Association of Smoking, Comorbidity, Clinical Stage, and Treatment Intent With Socioeconomic Differences in Survival After Oropharyngeal Squamous Cell Carcinoma in Denmark

IMPORTANCE: The socioeconomic gap in survival after cancer is pronounced among patients with head and neck cancer. Understanding the mechanisms of this gap is crucial to target intervention strategies. OBJECTIVE: To investigate socioeconomic differences in survival after oropharyngeal squamous cell carcinoma (OPSCC) according to human papillomavirus (HPV) status and the extent to which smoking, comorbidity, clinical stage, and treatment intent explain the survival gap. DESIGN, SETTING, AND PARTICIPANTS: This nationwide, population-based cohort study was based on prospectively collected information on all patients with a diagnosis of OPSCC from the Danish Head and Neck Cancer Group database and administrative registries. The study included 4600 patients born in 1921 or later, aged 30 years or older, and residing in Denmark 1 year prior to OPSCC diagnosis. Patients with missing information (547 [12%]) were excluded. Patients were diagnosed between January 1, 2008, and December 31, 2019, and followed up until December 31, 2021. Data were analyzed from June 6 to October 4, 2022. EXPOSURE: Socioeconomic position (educational level, disposable income, or cohabiting status). MAIN OUTCOMES AND MEASURES: Socioeconomic differences in 5-year overall survival were estimated in Cox proportional hazards regression models by HPV status. The indirect effect and proportion mediated by smoking, comorbidity, clinical stage, and treatment intent were estimated based on a counterfactual approach. RESULTS: The analyzed cohort comprised 4053 patients (1045 women [26%] and 3008 men [74%]). The median age was 61 years (IQR, 55-68 years), and 2563 patients (63%) had HPV-positive OPSCC while 1490 patients (37%) had HPV-negative OPSCC. The 5-year standardized overall survival was 10% to 15% lower among patients with a lower educational level, with low disposable income, or who were living alone (patients with HPV-positive OPSCC, 68%-71%; patients with HPV-negative OPSCC, 31%-34%) than patients with a higher educational level, high disposable income, or a cohabiting partner (patients with HPV-positive OPSCC, 81%-86%; patients with HPV-negative OPSCC, 43%-46%). Among patients with HPV-positive OPSCC, a considerable part of this survival gap was estimated to be associated with differences in smoking (27%-48%), comorbidity (10%-19%), clinical stage (8%-19%), and treatment intent (16%-28%). Among those with HPV-negative OPSCC, comorbidity (12%-22%) and treatment intent (16%-42%) were the primary potential mediators. CONCLUSIONS AND RELEVANCE: This cohort study suggests that, regardless of HPV status, patients with low socioeconomic position had 10% to 15% lower 5-year overall survival than patients with high socioeconomic position. A substantial part of this survival gap was associated with differences in smoking, comorbidity, clinical stage, or treatment intent at diagnosis.