Introduction

In the U.S., oropharyngeal cancer (OC) rates are increasing with an estimated 54,000 new cases in 2022 and over 11,000 deaths. In Texas, the OC rate was 10.9 cases per 100,000 people and almost 22,000 residents living with OC. Dental providers, such as dentists and dental hygienists, may have a role in reducing OC rates through prevention and screening. In Texas, there are a significant proportion of dental health professional shortage areas (DHPSAs), a county-level measure calculated based on the number of dental professionals relative to the population with consideration of high need. Texas has 207 DHPSAs, impacting around 3 million people who may lack access to dental care, including OC prevention, screening, and early diagnosis. To further understand the relationship between dental providers and cancer diagnoses, we examined the association between OC incidence rates and DHPSAs in Texas.

Methods

We calculated OC incidence by selecting site of Texas from SEER-Medicare linkage data. Only patients diagnosed OC in 2012-2017 at aged 65 and over were included for the numerator. We used American Community Survey from the U.S. census to identify Texas population aged 65 over for the denominator. Incidence (rate per 100,000) by age group and gender for each county was estimated and stratified by DHPSA (yes/no). DHPSA was a surrogate variable identified from Texas FIPS counties linked to Area Health Resources Files provided by the Health Resources & Services Administration website. We used Poisson Regression models to account for difference of patient characteristics across counties. In addition, we accessed late stage OC diagnosis between DHPSA using a logistic regression model. OC was also stratified by cancer site diagnosed at an upper or lower site. All the analyses were conducted using SAS 9.4 version. 

Results

The OC incidence rate (all sites) was 21.8 per 100,000 people. Incidence rates were higher for cancers in more visible upper sites (lip, tongue, salivary gland, floor of mouth, and gum and other mouth; 19.3 per 100,000) than lower, less visible sites (nasopharynx, pharynx, tonsil, oropharynx, hypopharynx, and other oral cavity; 8.0 per 100,000).

DHPSA counties had lower OC incidence rates (24.3 per 100,000) than non-DHPSA counties (29.9 per 100,000; p=0.04). OC risk was significantly lower in DHPSA counties (aRR: 0.92; CI: 0.84-0.99) compared to non-DHPSA counties. Incidence rates for lower site cancer were lower in DHPSA areas than non-DHPSA counties (p=0.0030), and risk for lower site cancers was lower for those in DHPSA counties (aRR: 0.83 CI: 0.71-0.97) than non-DHPSA counties. Among patients with OC diagnoses, those living in a DHPSA county had lower odds of advanced stage OC diagnoses (aOR: 0.78; CI: 0.64-0.96) than those in non-DHPSA counties.

The OC incidence rate was higher among men (43.4 per 100,000) than women (15.4 per 100,000) and OC risk was also higher among men (RR: 0.35; CI: 0.33-0.37). Men in DHPSA areas had lower OC incidence rates (36.3 per 100,000) than men in non-DHPSA areas (49.3 per 100,000; p=0.035).

Conclusion

These results provide insight into the relationship between dental providers and OC diagnoses. DHPSA areas generally have better outcomes and lower incidence rates of OC, which indicates a complex relationship between these variables. With limited dental providers to identify and refer patients for care, cancers may not be diagnosed, and the true OC rates are not reflected. Data availability regarding dental services usage is lacking among this sample as people may be traveling outside their respective counties to seek oral care due to limited local resources. These data provide opportunities for further investigation, particularly around dental service utilization and diagnoses. By understanding the unique individual pathways to receiving an OC diagnosis, leverage points, including intervention by dental professionals, can be prioritized to improve OC outcomes.