African-Americans have fewer incidences of thyroid cancer but have a more advanced form of the disease once they receive a diagnosis - and are more likely to die from it, according to a new study.
"We think that the mortality rate is probably due to an access to care issues," said Christopher Hollenbeak, Ph.D., lead study author. His study found that African-Americans had a 1 percent higher mortality rate, though thyroid cancer is twice as common among whites.
"African-Americans were more likely to present with tumors larger than four centimeters, which implies that the tumors sat there and grew a lot longer," he said. His study also found they were more likely to present with anaplastic thyroid cancer, which is a fatal and advanced form of the disease, as opposed to papillary and medullary cancer, which are most common and easily treated.
The study appears in the Spring issue of the journal Ethnicity & Disease
. The authors analyzed the National Cancer Institute''s registry data from 1992 to 2006 that tracked five-year survival rates of thyroid cancer patients. The registry currently represents 17 states, but reflects national cancer trends, said Hollenbeak, an associate professor of surgery and public health sciences at Penn State College of Medicine. Among nearly 27,000 patients, fewer than 2,000 patients were African-American and the rest were white.
"Part of this reflects the difference in distribution between the races. You just don''t see thyroid cancer much among blacks as you do among whites," said Hollenbeak. He added that while the 1 percent difference might seem insignificant, the study''s collective findings - that African-Americans more often present with an advanced form of the disease - indicates a disparity in care that should be addressed with policy change.
But Susan Shaw Devesa, Ph.D., a National Cancer Institute epidemiologist who is not affiliated with the study, views the findings from a different perspective. Comparing data of both racial groups with the same disease classifications, she noted the higher rate of papillary tumors in whites. "The data suggest that there is little racial disparity in survival when tumor type and size are accounted for," she said.
According to David Goldenberg, M.D., senior author of the study, thyroid cancer is the seventh most common type of cancer nationally and is on the rise. It most commonly occurs in female patients in their 40s, and is also frequently diagnosed in Asians but less so among Hispanics.
"The prevailing theory today is that anaplastic is thyroid cancer that goes haywire from not being treated," said Goldberg, an associate professor of surgery and oncology at Penn State College of Medicine.
Thyroid cancer is typically symptomless, said Goldberg. Treatment involves a thyroidectomy - partial or complete removal of the thyroid gland - and some patients receive radioactive iodine. With early detection and treatment, he said, the disease is 90 percent curable.
According to the authors, it''s speculated that the cancer is caused by environmental factors such as X-ray exposure. But the authors also said that the uptick in incidences might be due to more effective diagnostics.