Racial/Ethnic Differences in Head and Neck Cancer Survival Rates

Abstract

Background: Head and neck cancer (HNC) is the eighth most common cancer in the male population in the U.S. It is more common in men than women, and it usually affects adults ages 40 to 60. The main risk factors are tobacco and alcohol consumption and HPV infection. It is also known that race/ethnicity, social determinants of health (SDOH), and oral health influence the prevalence of HNC. Regarding its prognosis, the most important factors related to survival are the tumor site, the clinical stage at diagnosis, and proper treatment given timely. Despite all the advances in treatment for head and neck cancer in the last 30 years, survival rates have not increased at the same pace, nor are they the same in different populations. Recently, researchers have investigated how the risk factors of HNC can also affect survival. Some studies have looked for the association between race/ethnicity, SDOH, and other patient- and tumor-related factors and the occurrence of HNC but have also used those factors as predictors of patients' lives after the HNC diagnosis, producing a much more complex understanding of survival outcomes and maybe justifying why advances in treatment have not been enough to improve survival across all population. The aim of this study is to investigate the racial/ethnic differences in head and neck cancer survival rates observed in the US in recent years, and its possible association with patient and tumor characteristics, and SDOH. Methods: This is a retrospective study based on patients registered from 2007 to 2014 in the 18-cancer registry dataset of the SEER Public-Use Data from the Surveillance, Epidemiology, and End Results (SEER) Program. Selection criteria included patients aged 18 or older, with a diagnosis of invasive squamous cell carcinoma localized at the oral cavity, oropharynx, hypopharynx, or larynx. In addition to the individual (including clinical data) and county-level data obtain from SEER, other county-level attributes were obtained from: the National Center for Education Statistics, the U.S. Census Bureau’s – American Community Survey, and the Community Health Rankings. Statistical analysis was performed on the Statistical Package SPSS version 23. Data distribution was described in tables regarding the main variables. The association of these variables with race/ethnicity was evaluated by the chi-square test. For the cancer-specific survival analysis, the Kaplan-Meier method (and the log-rank test) as well as the Cox proportional hazards model were used. For all statistical tests, the significance was 2-sided and achieved when p-values ≤ 0.05. Results: The final sample size included 59,853 head and neck cancer patients. The majority of the patients were White (76.4%), followed by Blacks (11.2%), Hispanics (7.7%), Asian or Pacific Islanders (4.2%), and American Indians/Alaska Natives (0.5%). The tumors were localized predominantly at the oropharynx (41.6%) as is usually the case with patients at an advanced clinical stage (62.9%). The most common treatment performed was radiotherapy (with or without chemotherapy – 42.5%). For all socio-demographics characteristics evaluated (age, gender, marital status, area of residence, and health insurance), clinical characteristics (tumor site, clinical stage, and treatment), county-level SDOH attributes (age distribution, poverty, unemployment, income, GINI index, education, health literacy, nationality status, and linguistic isolation), and county scores (health outcomes, health behavior, clinical care, social and economic factors, and physical environment), statistical differences were found when comparing the distribution of all these variables between races/ethnicities, with Whites presenting, overall, a more favorable distribution with regard to patient, tumor, socioeconomic, and county-level attributes. Blacks displayed the less favorable, Asian/PI, Hispanics and AI/AN presented a mixed distribution depending on the variable being evaluated. In the univariate survival analysis, all races/ethnicities showed a higher risk of dying of cancer than Whites (p<0.001). Blacks, in particular, presented a much worse risk of death due to the disease, HR 1.799 (95%CI, 1.722–1.879), for Hispanics the HR was 1.231 (95%CI, 1.161 – 1.304), for Asian/PI the HR was 1.096 (95%CI, 1.011 – 1.187) and for AI/AN the HR was 1.318 (95%CI, 1.077 – 1.613). When we first adjusted for patients' characteristics (age, gender, marital status), all races/ethnicities still showed a higher risk of dying due to cancer than Whites (p<0.001). In the subsequent multivariate analysis, when tumor characteristics (tumor site, clinical stage, and treatment) were added to the model, the risk of death from cancer was no longer statistically significant for AI/AN population (HR 0.954, 95%CI 0.761 – 1.195; p=0.680), compared to the Whites, but still higher for Blacks (HR 1.329, 95%CI 1.267 – 1.393; p<0.001), Hispanics (HR 1.135, 95%CI 1.068 – 1.206; p<0.001), and Asian/PI (HR 1.099; 95% CI 1.008 – 1.195; p=0.033) when compared to Whites. The next model, further adjusted by the county-level SDOH variables, showed that Hispanics (HR 1.053, 95%CI 0.991 – 1.120; p=0.097) and Asian/PI (HR 1.045, 95%CI 0.958 – 1.140; p= 0.318) no longer had a worse prognosis than Whites, but Blacks still showed a 20% higher risk of dying from cancer than Whites (HR 1.227, 95%CI 1.169 – 1.288; p<0.001). The other factors associated with survival in the model were marital status (p<0.001); health insurance (p<0.001); county-level clinical care score (p=0.024); and county-level social & economic factors score (p<0.001). Conclusion: Our study showed that race/ethnicity plays an important role in HNC survival rates. Investments in HNC early detection, and more timely receipt of treatment would decrease the excess death risk by roughly half for all races/ethnicities (including Blacks) when compared to Whites. Further investments and policies related to socioeconomic factors, clinical care and towards decreasing social inequalities (including health care access) would further bring similar prognosis for Whites, AI/AN, Asian/PI, and Hispanics, and reduce the excess risk for Blacks by another 35%. If all this combined effort would be enough to bring comparable survival rates to Blacks, based on the complexity related to their heath access and social interactions, how much can be justified by individual’s genetics or tumor biology still warrants more investigation.