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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.” 
Learn more about the Southern Community Cohort Study at www.southerncommunitystudy.org.
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