SAN FRANCISCO – Nonwhite patients with well-differentiated thyroid cancer were at least 36% more likely than were whites to present with metastatic disease, and these significant racial disparities could not be explained fully by differences in socioeconomic status or other obvious factors in a study of 25,945 California cases.
The risk of remote (metastatic) disease at presentation was 89% higher in Hispanics, 82% higher in Asians or Pacific Islanders, and 36% higher in non-Hispanic blacks than in whites, Dr. Avital Harari and her associates reported at the Endocrine Society’s Annual Meeting. The investigators adjusted for the effects of age, socioeconomic status, sex, and type of insurance when assessing the effects of race on disease stage at presentation.
The odds of regional-stage disease at presentation also were significantly higher compared with whites among Hispanics (a 59% higher likelihood of regional disease) and Asian/Pacific Islanders (32% higher).
Compared with patients with the highest socioeconomic status, those with the lowest socioeconomic status were 45% more likely to present with remote disease, a significant difference. Patients who were poorly insured, uninsured, or covered by Medicaid insurance were more than twice as likely to present with remote disease as were privately insured patients. Age and sex increased risk too, with double the odds of metastatic disease at presentation in patients who were male or at least 45 years old.
"Despite the fact that three races seem to have presented with more remote disease than white patients, their survival analysis differs from what we might expect," Dr. Harari said. Asian/Pacific Islanders were significantly less likely than whites to die (a 14% lower odds ratio), and Hispanics had essentially the same overall survival rates as whites. The risk of death was significantly higher in black patients, who were 38% more likely than whites to die, after adjustment for the effects of age, sex, and comorbidities, said Dr. Harari, an endocrine surgeon at the University of California, Los Angeles.
Remote disease quadrupled the odds of dying and regional disease increased the risk of death by 46% compared with localized disease at presentation. Older age significantly increased the risk of death by 7%.
Among patients with metastatic disease at presentation, overall survival rates were not significantly different between racial groups after adjustment for age, sex, and comorbidity. Older age significantly increased the risk of death by 5%.
The chances of dying of thyroid cancer, however, were significantly greater for blacks than for patients of other races.
Differences in the biology of thyroid disease by race, disparities in access to care and resources that might delay diagnosis and treatment, and inherent provider bias are likely at play, said Dr. Harari.
"I challenge you to think about how you might change your practice in regard to the information noted here," she said.
Dr. Harari and her colleagues analyzed data on all new cases of thyroid cancer during 1999-2008 from the California Cancer Registry, a population-based cancer surveillance system. Cases were excluded if they were not well differentiated, had unknown stage at diagnosis, or were second cases in patients already in the registry. The researchers scored socioeconomic status using Yost’s index and scored comorbidity using the Charlson system.
The cohort was 57% white, 24% Hispanic, 15% Asian/Pacific Islander, and 4% black. The racial groups differed significantly by mean age, sex, mean comorbidity score, and socioeconomic score.
Hispanics were younger at diagnosis (mean age, 44 years) compared with Asian/Pacific Islanders (48 years) or whites or Hispanics (50 years each). Hispanics were less likely to be male (18%) than were whites (26%). Mean Charlson comorbidity scores were highest for blacks (0.69) compared with whites (0.41), Hispanics (0.39), and Asian/Pacific Islanders (0.34). Overall, black patients were more likely to be older and to have higher comorbidity scores than other patients, she said.
The two highest quintiles of socioeconomic scores included 60% of whites and 55% of Asian/Pacific Islanders. The two lowest quintiles of socioeconomic scores included 55% of Hispanics and 47% of blacks.
The results support a 2012 review by the Endocrine Society in which people with low socioeconomic status were more likely than more affluent groups to present with advanced thyroid cancer. That study also found that racial minorities had less access to high-volume thyroid surgeons (J. Clin. Endocrinol. Metab. 2012;97:E1579-639).
Dr. Harari reported having no financial disclosures.
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