Study reveals cancer diagnosis is more deadly in blacks
A study on deaths among people diagnosed with cancer gives a grim picture of survival among African Americans, according to researchers at the University of South Carolina’s Arnold School of Public Health.
One of the nation’s first studies to track the ratio of deaths based on the incidence of specific cancers, the report in the June 1, 2009, issue of the journal Cancer yields a powerful measure of the scope of the cancer problem among men and women, whites and blacks.
Researchers examined the eight public-health regions in South Carolina for the number cancer deaths among people diagnosed with cancer from 2001 to 2005 and then compared these numbers to corresponding national rates.
Although the study was done in South Carolina, it could be replicated in other states or regions by using cancer incidence and death data, said James Hebert, the study’s lead author and a professor in the Arnold School.
Comparing and mapping race- and sex-specific cancer “mortality-to-incidence ratios” (MIR) provide a powerful method to observe the scope of the cancer problem, he said.
African Americans had much higher mortality rates than whites even when a specific cancer had a lower incidence rate, Hebert said. For example, S.C. data reveal that African Americans smoke less than whites. But statistics on oral cancer show that African Americans have a higher MIR in seven of the state’s regions.
“Comparing these data to national MIR rates shows the severity of the problem,” said Hebert.
“We already knew that South Carolina provides dramatic examples of health disparities,” said Hebert, who also serves as director of the USC-based South Carolina Statewide Cancer Prevention and Control Program. “This study is alarming. However, in showing health disparities in a visual, graphic way in geographic space it also points a way toward potential solutions.”
While cancer disparities between whites and African Americans are stark, there is a glimmer of good news on the cancer front in the Palmetto State. Susan Bolick-Aldrich, a co-author on the Cancer paper and director of South Carolina’s Central Cancer Registry, said the overall incidence of cancer and cancer mortality rates in the state declined from 1996 to 2005.
"Mortality rates from all cancers decreased by 18.2 percent during that time period, and incidence of all cancers declined by 3.2 percent,” Bolick-Aldrich said. “Even so, we’re seeing increases in the incidence of certain cancers such as lung cancer in demographic sub-groups, specifically white women.”
Virginie Daguise, another author of the Cancer article and a cancer epidemiologist at the S.C. Department of Health and Environmental Control and adjunct faculty member in the Cancer Prevention and Control Program and the Department of Epidemiology and Biostatistics, oversees the compilation of the state’s cancer report card. The first such report came out in 2004 and looked at 19 different types of cancer; the next report card will come out later this year and will focus on nine cancers and address accomplishments and future direction.
"We don’t want to simply report more data this year but instead want to explore where we go from here,” Daguise said. “Some people will want to find answers as to why the numbers are what they are; others will want to do more in terms of public education, screening, awareness, and getting buy-in from communities on strategies to address the problem.”
Other study findings:
- Racial differences: The largest racial differences are for prostate, oral and female breast cancers. African Americans had MIRs nearly twice those of whites.
- Female breast cancer: The MIR for breast cancer among white females is at the national average or below for all but two regions – the Pee Dee and the region around Orangeburg to the Savannah River Site – of South Carolina. Among African-American females, the MIR is at between 10 and 20 percent higher than the national average in one region and more than 20 percent higher in the state’s remaining seven regions.
- Colorectal cancer: Colorectal cancer MIRs for white men and women is at the national average or below in every part of the state. But for African Americans living in the Pee Dee and the counties along the Grand Strand and Lowcountry, the MIR is above the national average by at least 20 percent.
- Oral cancer: Among whites, only one region of the state is more than 20 percent higher than the national average for oral cancer. This region includes Aiken, Barnwell, Calhoun, Orangeburg, Bamberg and Allendale counties. However, the oral cancer MIR for African Americans is greater than 20 percent of the national average in all but four counties: Hampton, Colleton, Jasper and Beaufort. These four counties are about 10 percent higher than the national average.
- Prostate cancer: In 43 of the state’s 46 counties, the MIR for lung cancer among African Americans is more than 20 percent of the national average. The remaining three counties – Williamsburg, Georgetown and Horry counties – are 10 to 20 percent higher than the national average.
- Lung cancer: The MIR for lung cancer among whites was at or below the national average for the three regions along the coast of South Carolina and up to 10 percent higher for the remaining five regions. Among African Americans, however, only three counties in the Palmetto State – Charleston, Berkeley and Dorchester counties – were at the national average. The remaining 43 counties were above the national average.
Hebert said the study does not explain the cause of the racial and sex differences among the cancer rates.
“It may be that African Americans are getting a particularly virulent type of cancer,” he said. “They may be diagnosed at later stages or not getting follow-up care after a cancer diagnosis. We don’t have those answers.
"But this study does give public-health and other healthcare professionals a better understanding of the areas of the state with the greatest cancer incidence and deaths due to cancer. It shows where we need to target our resources.”