The Cancer Belt: Beneath the Veneer of Southern Hospitality Lurks a Silent Killer
July 14, 2008
By Dagny Stuart (from the Spring 08 Momentum)
The South is known for many things – hot, steamy summers, iced tea laced with sugar and friendly people with a tendency to welcome strangers. But beneath the veneer of Southern hospitality and gracious living lurks a silent killer. Cancer is more prevalent in the South, and death rates, especially among African-Americans, are alarmingly high. Cancer researchers have their own name for the Southern region of the United States – The Cancer Belt.
Brain cancer is just one of the malignancies disproportionately affecting people who live in Southern states. Glioma, also known as glioblastoma, may be rare but it is lethal. Ninety-five percent of patients die within two years of diagnosis. “When you look at a map of brain cancer incidence in the United States, the Southeast just lights up in red,” said Reid Thompson, M.D., associate professor and vice-chair of the Department of Neurological Surgery. “When we found this hot-spot on the National Cancer Institute’s mortality maps, we realized something unusual is going on in this region.”
Thompson and co-investigator Kathleen Egan, M.P.H., Sc.D., have launched a study to find clues that may explain this brain cancer cluster. (Egan, formerly of Vanderbilt-Ingram Cancer Center, is now on faculty at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla.) Vanderbilt-Ingram, along with four other cancer centers in the region, will enroll as many as 1,000 patients in the federally funded initiative.
“We’re asking patients about their diets, possible job-related exposure to cancer-causing chemicals and we’re collecting DNA samples,” explained Thompson, who also serves as director of Vanderbilt’s Brain Tumor Center. “We know there are some genetic markers that are linked to other forms of cancer and they may play a role in brain cancer, as well.”
Brain cancer isn’t the only cancer taking an unusual toll on Southern populations. Several forms of cancer strike Southerners more often than people who live in other sections of the country. Topping the list is lung cancer. Despite decades of warnings about the dangers of cigarette smoking, Southerners continue to smoke more than those in other regions of the country and, as a result, they are far more likely to be diagnosed with lung cancer.
Cancers of the mouth and throat also are linked to tobacco use, and once again those cancers are more prevalent in Southern states.
“Instead of cigarettes, it is the use of snuff and chewing tobacco – among women as well as men – that causes this spike in oral cancers,” according to William Blot, Ph.D., professor of Medicine. “There are still parts of the South, especially rural areas, where snuff use is fairly common among women.”
Behavior like tobacco use is clearly linked to the development of some forms of cancer. But it is less easy to explain why people living in the South are developing many types of cancer at higher rates than folks who live in other regions of the country. And it doesn’t explain why African-Americans are more likely to develop some forms of cancer and are more likely to die from the disease.
So Blot is leading the Southern Community Cohort Study (SCCS), the largest epidemiologic study in history to explore why the South has become the Cancer Belt and why African-Americans experience higher rates of many types of cancer. Starting with a $28 million grant from the National Cancer Institute, the SCCS hopes to recruit 90,000 people in 12 Southern states to learn about their lifestyles, their medical histories and their risk factors for cancer and other serious diseases. Two-thirds of the participants will be African-American and many will be from rural areas.
The SCCS is a collaborative project among Vanderbilt-Ingram, Meharry Medical College and the International Epidemiology Institute, as well as participating community health centers across the South.
“The study participants form one of the groups at highest risk for cancer that has ever been studied,” explained Blot. “Most other investigations have not included large numbers of African-Americans and few have included low-income individuals and people from rural parts of the country. This is the first large-scale study and the first in the South to include large numbers of all of those groups.”
All in the Family
The SCCS is designed to be a longitudinal study of this Southern population cohort. Each participant is interviewed and asked about their family background, medical history, diet, smoking habits and work environment. Every four years, researchers will do follow-up interviews, looking for new cancer cases or other diseases and trying to find the patterns of behavior, exposure to carcinogens or other clues that could explain why cancer is so prevalent in the region.
Alice Smith of Antioch, Tenn., was determined to sign up for the study when she visited the Matthew Walker Comprehensive Health Center in Nashville because cancer has forged a deadly legacy in her African-American family.
“Cancer took out the majority of the women on my mother’s side of the family, so whenever there is anything to do with cancer I always get involved,” she explained. Smith, 54, says her mother, grandmother, sister and several aunts were diagnosed with various types of cancer including breast, throat and pancreatic cancer.
“The doctors keep saying it’s hereditary, so I try to eat healthy and take care of myself,” said Smith. She also sees her doctor often, especially after she was diagnosed with multiple sclerosis. She hopes that her participation in the SCCS will help scientists determine the factors that contribute to so many serious illnesses in her own family and other families across the South.
“If they can figure out what’s causing it, they might be able to find some things you can do to prevent it,” Smith said with hope in her voice. “I’m very concerned about my health because I want to be here for a long, long time.”
Cancer in the Neighborhood
The focus on African-Americans is long-overdue, especially since this group has much higher mortality rates for many forms of cancer. Even when the incidence of a certain form of cancer is higher among whites, the survival rate is nearly always lower for blacks. The reasons are not clear, but suspected culprits include differences in access to screening or treatment, stage at diagnosis, and aggressiveness of disease.
Breast cancer is a good example of this anomaly. While white women in states like Tennessee are slightly more likely to be diagnosed with breast cancer than African-Americans, African-American women are far more likely to die from the disease.
“In the 1990s, women in the African-American community were telling me that younger women were being diagnosed with breast cancer, especially aggressive forms of breast cancer, but I don’t think researchers were always listening to the community,” explained Elizabeth A. Williams, Ph.D., associate director of Minority Affairs for Vanderbilt-Ingram. “Now scientists have discovered that aggressive forms of breast cancer are disproportionately affecting African-American women. If as scientists we’re off in our ivory towers and are not listening carefully to people affected by cancer, we can miss opportunities for early diagnosis, prevention and control. Research and communication is not a one-way street. It is a two-way street between scientists and communities and we need to recognize that.”
Williams said it is becoming clear that the burden of cancer is being borne disproportionately by people of color. This health care disparity has its roots in the tangled web of the South’s political and social history, including segregated housing patterns. People living in low-income neighborhoods may find it more difficult to adopt a lifestyle that can protect them against some cancer risk factors.
“We do know there is a significant lifestyle component linked to cancer incidence,” said Bettina Beech, Dr.P.H., associate director of Health Disparities Research for Vanderbilt-Ingram. “If we increase fruit and vegetable consumption, decrease fat consumption and increase physical activity, we can avoid a huge percentage of cancer cases. But it is not that simple for people living in some areas. For low-income individuals, regardless of whether they are minorities, there is reduced access to grocery stores with high-quality produce in many neighborhoods. By the same token, if they don’t have sidewalks or safe neighborhoods, those structural environmental issues impede their ability to be physically active.”
Beech points out that those same low-resource neighborhoods may have drive-through liquor and tobacco stores that are close to schools and housing developments. She believes this easy access to unhealthy products isn’t as prevalent in high-resource areas.
Gaps in access to health care, both for low-income individuals as well as minorities, also exist, Williams said.
“Historically, when you look at people of color in relation to the majority population, we have always had a two-tiered medical system in the United States, particularly in the Southern states,” said Williams. “What continues to persist is differences in the way people are perceived within the health care system. That has an effect on how people access the health care system, whether or not they actually make it to the front door of the system, and how they are received once they do arrive.”
Beech points to a 2002 study on unequal treatment by the Institute of Medicine which found clear-cut evidence that longstanding racial attitudes affect patient treatment.
“The literature has consistently shown this disparity in treatment and access,” Beech said. “The IOM report demonstrated that even when providers are presented with fictitious patients with the same patient profile, with race as the only difference, physicians often provided a different diagnosis, different prognosis and different course of treatment for the patients.”
Genes Play a Role
While lifestyle factors and access to preventive surveillance and treatment play a role in cancer, scientists increasingly are finding genetic differences that may explain some of the disparities.
Consider the surging number of prostate cancer cases among African-American men compared with white men.
African-American men are far more likely to be diagnosed with prostate cancer than white men, and the death toll is even more alarming, with African-Americans more than twice as likely to die from the disease. Researchers discovered a combination of genes that appear to play a role in the aggressive forms of the disease often found among black men.
The skin pigmentation differences associated with race may play more than a cosmetic role in some forms of cancer. Dark pigmentation may hinder and light skin may help the body’s ability to produce vitamin D.
“It’s been speculated for a number of years that vitamin D may play a protective role in cancer,” Blot explained. “Researchers have found lower blood levels of vitamin D among people living at northern latitudes, and those populations are more likely to develop certain forms of cancer. Since we know that exposure to sunlight helps the body produce vitamin D, it stands to reason that someone with dark skin may not be getting enough of the vitamin. Our study in the South found roughly half of the African-American population had insufficient levels of vitamin D versus only 10 to 15 percent of the white population.”
If researchers can determine exactly how vitamin D influences cancer risk, they may be able to supplement the diets of those who have insufficient levels of the vitamin.
This search for genetic variables is just one of the reasons the Southern Community Cohort Study includes DNA samples. Each participant is asked for a blood and urine sample. Those who prefer not to give blood are asked to use a mouth rinse, from which researchers can extract DNA. The samples collected in all 12 states are shipped to Vanderbilt for long-term secure storage.
This database of biologic specimens serves as a treasure trove for scientific investigators. With each new discovery, researchers can study the intricacies of those DNA samples, looking for the patterns that confirm or refute the new findings.
“Collecting those specimens is absolutely critical to the success of this project,” Blot enthused. “The way biology and medicine are moving, eventually we’re going to be in a world of individualized medicine, individualized treatment and individualized prevention. To do that you really must have biologic information on patients.”
The discoveries unearthed by this and other studies of human biology should play a role in enhancing cancer care, especially for people living in the South. But that same information must be used to draw a new roadmap for delivery of high-quality care to every demographic group.
“It is essential that everyone benefit from this kind of high-impact scientific research,” said Jennifer Pietenpol, Ph.D., professor of Biochemistry and director of Vanderbilt-Ingram. “We owe it to our patients and to future generations to ensure that the lessons we learn as scientists are shared with everyone who walks through our doors.” bullet
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