Factors associated with unknown primary status in head and neck squamous cell carcinoma

Head and neck cancer of unknown primary (CUP) poses significant therapeutic challenges. We compare CUP and oropharyngeal primary (OP) cases to identify factors associated with tumor detection.

The 2004-2019 National Cancer Database was queried to identify CUP and OP cases based on clinical and pathologic TNM staging. Clinical and demographic characteristics were compared by primary detection and HPV status with descriptive statistics. Multivariable logistic regression models to characterize OP detection were constructed. Among HPV-positive and negative patients, respectively, OP and CUP patients were matched by clinical nodal disease. Cox proportional-hazards models were constructed using matched cohorts to characterize survival.

81,053 CUP and OP cases were identified; 64.3 % were HPV-positive. OP detection increased over time in HPV-positive and negative disease. HPV-positive status had higher odds of OP detection (odds ratio (OR) = 1.77, p < 0.001), while females (OR = 0.95, p = 0.008), and black (OR = 0.82, p < 0.001) and Asian (OR = 0.7, p < 0.001) patients had lower odds compared to males and whites, respectively. In HPV-positive and negative disease, OP patients had higher 2 and 5-year survival rates than CUP (p < 0.001). Primary detection status conferred lower death risk in HPV-positive (hazard ratio (HR) = 0.85, p < 0.001) and negative disease (HR = 0.87, p < 0.001) when controlling for age, sex, race, comorbidities, insurance, treatment facility, and income.

In the largest cohort of CUP to date, we report a survival benefit in primary tumor detection regardless of HPV status. Groups with higher persistent CUP rates, including non-white, female, HPV-negative, and low income patients, may benefit from increased diagnostic workup to improve detection and treatment.