In patients with well-differentiated thyroid cancer (WDTC) those with low socioeconomic status have more advanced disease than those with higher socioeconomic status; and black patients consistently present with later disease and have worse overall survival rates than other racial groups. That is the conclusion of a new study published in the Journal of Endocrinology and Metabolism (2014;99:133-141).
“This is one of the most comprehensive studies on this topic in the literature—and it confirms that all minority patients and those with lower socioeconomic status present with more advanced disease than white patients do,” the study's lead author, Avital Harari, MD, Assistant Professor of General Surgery in the Endocrine Surgery Unit at the David Geffen School of Medicine at UCLA, said via email.
“What is surprising, however, is that Asian and Hispanic patients may actually have a protective effect on survival despite presenting with more advanced disease.”
The retrospective cohort study analyzed the outcomes of 25,945 patients with well-differentiated thyroid cancer from the California Cancer Registry (which included 14,802 non-Hispanic white patients, 939 non-Hispanic black patients, 6,303 Hispanic patients, and 3,901 Asian-Pacific Islander patients), making it the largest comprehensive study of this kind, the researchers noted.
For the study cohort, the following were the major findings:
- The unadjusted analysis confirmed that minority groups had a higher odds of presenting with remote/metastatic disease compared with white patients, and after adjusting for age, sex, socioeconomic status, and insurance type, minority groups continued to have an increased odds of presenting with remote/metastatic disease compared with white patients;
- Patients with the lowest socioeconomic status presented with remote or metastatic disease more often than those with the highest socioeconomic status, and as socioeconomic status increased there seemed to be decreasing odds of presenting with remote or metastatic disease;
- Patients who were poor or uninsured (and/or with Medicaid insurance) had a higher odds of presenting with remote or metastatic disease than those with private insurance;
- Older patients (those over 45) were more likely to present with remote or metastatic disease than those in the younger age group;
- Unadjusted overall survival rates were higher among Asian-Pacific islander, and Hispanic patients, and lower among black patients, and after adjusting for stage, age, sex, comorbidities, and treatment variables, there was a persistent survival advantage for Asian patients, and a survival disadvantage for black patients; and
- Out of all patients with remote or metastatic disease, black patients had the lowest overall and disease-specific survival rates.
Racial differences cannot be fully explained by patients' socioeconomic factors, age, sex, or insurance type, the researchers said. The data showed a persistent protective survival advantage in Asian-Pacific Islander and Hispanic patients despite those patients presenting with later-stage disease and despite having a lower percentage of males.
The researchers noted that some of the potential etiologies that could explain the disparities found were: inequality in access to care in resource-poor neighborhoods; differences in disease biology (black patients tended to have a larger tumor size on average than the other races); obesity, which has been shown to be an independent risk factor for thyroid cancer, is very prevalent in the black and Hispanic races; racial and ethnic discrimination (i.e. inherent provider bias resulting in dissimilar diagnostic procedures and/or therapies for the same disease process); and differences in environmental exposures and healthiness of lifestyles (such as the prevalence of smoking, misuse of alcohol and drugs, and presence of mental disorders).
“Hopefully, this work will lead to strategies to increase access to care and make those who treat thyroid cancer patients more aware of how aggressive this cancer can be in certain racial and socioeconomic groups, and reinforce the importance of being vigilant in their screening practices,” Harari said.