This analysis revealed that significant differences in disease severity at presentation exist within a diverse cohort of patients with PTC at a single-site urban institution and young age and low SES were independent predictors of Bethesda IV staging at initial presentation. Disease severity upon presentation to a healthcare provider is important in PTC because early-stage disease is typically curable. While most thyroid cancers have high survival rates, patients with advanced disease tend to have a poorer prognosis. Data has shown that patients who die secondary to thyroid cancer generally present with advanced disease.[27–29] Disease severity is also crucial in determining medical management, with fewer therapeutic options for patients with advanced disease. Some therapies more common in advanced disease, such as radiation and chemotherapy, may also lead to lower quality of life.
This study found that patients in the lowest SES quartile were most likely to present with cytologically confirmed malignancy, whereas patients in the highest SES quartile were the least likely to present with Bethesda VI. Our results are consistent with previous studies that describe an association between low SES and advanced PTC.[13, 17, 18, 30, 31] Interestingly, one study found that patients presenting to a public hospital were over three times more likely to present with advanced PTC when compared to patients presenting to a university teaching hospital.[32] Generally, lower SES is associated with reduced access to healthcare.[33–36] Patients with less access to care due to financial constraints may then present with disease later than their higher income counterparts and therefore initiate care with more advanced disease. Our results could therefore reflect a later date of detection in patients with lower SES potentially due to barriers in accessing care, such as the cost of testing or inability to take time off from work. This is consistent with prior research studying cancer patients and reporting that socioeconomically disadvantaged patients are most likely to report delays in initial presentation.[37]
Another possible connection between lower SES and presenting with advanced thyroid cancer could be related to a patient’s geographic residence, especially when using patient zip code as a proxy for SES. Almberk et al. for example found that patients living in rural areas were more likely to present with advanced thyroid cancer compared to those living in urban areas.[30] While all patients in the present study were from urban communities, there have been differences reported in the incidence of thyroid cancer within a single urban area, like New York City.[38] These studies appear to attribute the demonstrated differences to proximity or exposure to certain contaminants.[39–41] While research has focused primarily on the incidence of thyroid cancer, it seems clear that the environment could also modulate disease severity.[42, 43] One study, for example, found that exposure to higher levels of cadmium in Korean female patients was associated with advanced thyroid cancer.[44]
Our results differed from several studies that demonstrated race/ethnicity was associated with disease severity at presentation. A few studies have found that Asian and Hispanic patients are more likely to present with advanced disease compared to White patients, while adjusting for income level and insurance status.[12, 13] Interestingly, Bonner et al. reported that income was associated with advanced disease on univariate analysis, but after adjusting for other socioeconomic factors, income became associated with less advanced disease.[12] Our results also contrasted with the findings in Ullman et al., which reported that patients with private insurance were less likely to present with high-risk features of PTC compared to uninsured patients.[15] Instead, our study found that both race/ethnicity and insurance status were not significant predictors of presenting with Bethesda VI on FNA.
This analysis also demonstrated that younger patients tended to present with more advanced disease. Similarly, Harari et al. found that patients aged < 45 were more likely to present with high-risk disease.[13] This may not be unique to PTC, as prior research suggests that older patients with cancer may be less likely to delay their initial presentation to a provider.[37, 45] We hypothesize that the young population could be similar to patients with lower SES in that they may be less likely to visit a medical provider than their older counterparts, which has been reported in several studies.[46–49] However, while younger patients seem to present with more advanced thyroid cancer, studies have found that this does not lead to lower rates of survival in this cohort.[50] Rather, young age appears to be a prognostic factor for better overall survival.[51]
Our study aimed to focus on a diverse cohort of patients from one tertiary institution. This approach allowed us to validate specific patient information and investigate if national trends apply to this unique setting. However, this also resulted in a limited sample size, while similar studies utilized larger nation-wide datasets. Another possible limitation is our use of FNA as a measure of disease severity at presentation because it did not allow us to differentiate the extent of malignancy between patients. However, we were able to capture the true initial presentation to a provider, circumventing any possible delays in surgical treatment. Additionally, cytology using the Bethesda classification system has found to reliably predict advanced disease.[23–25]. Lastly, several patient factors were not included in our analyses that could have an influence on disease severity at presentation, such as patient health literacy, distrust in the healthcare system, extent of social support, and whether patients have a primary care provider. Given the retrospective nature of our study, we were unable to collect this level of detailed information for each patient.