Abstract
Purpose
Poorer survival from head and neck squamous cell carcinoma (HNSCC) in African Americans (AA) may be due to disparity in the prevalence of Human Papillomavirus (HPV) but earlier studies often failed to control other etiological factors. We aimed to elucidate whether racial disparities in HPV prevalence and overall survival were due to confounding from smoking or alcohol use.
Materials and methods
385 patients with SCC of the mouth, pharynx, nose, or larynx who had surgical resection at Wayne State University affiliated hospitals were identified through a population-based cancer registry. Formalin fixed paraffin embedded tissue blocks were used to determine the presence of HPV DNA and its genotype using a sensitive broad-spectrum PCR technique. Patients’ demographics, tumor characteristics and vital status were obtained through record linkage with the registry data and smoking and alcohol information was abstracted from medical record. Cox’s proportional hazard model and unconditional logistic regression models were employed to analyze the overall survival and tumor HPV-positivity, respectively.
Results
HPV positivity in oropharyngeal cancer was substantially lower in AA than in other racial groups (odds ratio 0.14, 95% confidence interval (CI) 0.05–0.37) and adjustment for smoking or alcohol did not change this association. However, a significantly increased hazard ratio of death in AA oropharyngeal cancer patients (univariable hazard ratio (HR) 2.55, 95% CI 1.42–4.59) decreased to almost unity (HR 1.49, 95% CI 0.75–2.93) after adjustment for HPV and smoking.
Conclusions
Lower HPV prevalence in AA largely accounts for their poorer survival from oropharyngeal cancer, but not other HNSSC.
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Introduction
Over 644,000 incident cases and 350,000 deaths of head and neck squamous cell carcinoma (HNSSSC) are estimated to occur every year worldwide . In the USA, HNSSCs account for about 3% to 5% of all cancers . In 2013 alone, an estimated 53,640 people will develop HNSSC, with 11,520 of these patients dying due to HNSCC . Despite the overall declining trend in the incidence of head and neck cancer, reflecting the decreasing trend in tobacco consumption , incidence of cancer from the oropharyngeal sites, especially the tonsil and the base of the tongue, is rising, most notably in ages 40–55 . Recently Human Papilloma Virus (HPV) has emerged as a contributing risk factor for HNSSC, specifically in the oropharynx . HPV-associated tumors tend to respond more favorably to chemoradiation, and have better outcomes than HPV-negative HNSSC . Moreover, racial disparities among African Americans and Non-African Americans exist in HPV-associated HNSSC . The National Cancer Institute defines racial disparities as adverse differences in incidence, prevalence, mortality, survivorship and tumor burden. According to the 2010 US Census Bureau, the black population grew 15.4% from 2000 to 2010 and make up 13.6% of the US population . African Americans show a 50% higher age-adjusted HNSSC mortality rate compared to whites, with younger age at onset, more advanced stage at diagnosis and poorer survival in blacks than in whites .
Socioeconomic factors , less access to health care, high-risk sexual practices , host immunity/genetics , and tobacco and alcohol consumption have all been linked to racial differences . However the reason for racial disparities between incidence and outcome is still not fully elucidated. Racial differences in HPV prevalence in HNSCC have been reported and these differences have been attributed to poorer survival in African American patients . The objective to our study is to extend our previous cancer-registry based study in order to reevaluate the effects of race on HPV prevalence and overall survival in HNSCC patients, by taking advantage of more detailed information about smoking and alcohol drinking that could be retrieved from individual medical records.
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