Multiple Factors

Health disparities related to cancer are caused by a multitude of factors that create worse outcomes for people of color, including limited access to health care and screening, environmental and lifestyle factors, institutional racism, implicit bias, fear and mistrust, language barriers, lack of transportation, and more.

One of the many factors influencing cancer disparities is biology. “At the biological level, it can go in either direction,” Patierno says. For example, White people are more likely than African Americans to be diagnosed with bladder cancer, while the reverse is true for kidney cancer.

“If we can identify risk factors that might be associ­ated with where and in which direction a particular patient’s ancestors left Africa—and we’re all out of Africa—that ancestral lineage might help us identify people who may be at higher risk for specific cancers, aid in prevention and early detection efforts, and help us identify novel targets for drugs,” Patierno says.

Stomach Cancer: A bacterium is only part of the story

The vast majority of cases of stomach cancer in the United States are caused by infection with Helicobacter pylori. In some people, the bacterium causes no symptoms, but in other people it causes ulcers, inflammation, and other kinds of damage that can eventually lead to cancer.

About 3 percent of people with H. pylori will develop stomach cancer; clearing up the infection with antibiotics cuts that risk in half.

The incidence of ulcers and stomach cancer has declined over the past century as improved hygiene and the use of antibiotics have cut down on the prevalence of H. pylori. But neither H. pylori nor stomach cancer have been eliminated, and both the bug and the disease are more common among African Americans than Whites.

That really bothers Meira Epplein, PhD, an associate professor in population health sciences and medicine (medical oncology) whom Patierno describes as “one of the leading experts on H. pylori in the world.” She calls stomach cancer “highly preventable.”

However, H. pylori is only part of the story, because African Americans with the infection are more likely to develop stomach cancer than Whites with the infection. Other risk factors for stomach cancer include smoking, a high-salt diet, and family history. Researchers suspect that the biology plays a role as well: It may be that certain strains of V Cc are more carcinogenic than others or that certain aspects of a person’s immune response create conditions that encourage cancer.

“We’re trying to figure out the biology behind what’s happening,” says Epplein, who is coleading the stomach cancer project with Katherine Garman, MD, associate professor of medicine (gastroenterology).

The researchers will analyze a large number of previously banked tissue specimens from people who had H. pylori along with information about their disease and lifestyle factors such as smoking. They will also invite patients who are scheduled for upper endoscopies (in which a physician examines the lining of a patient’s esophagus and stomach with a flexible tube and camera) to fill out a detailed questionnaire, donate tiny tissue samples, and agree to let the researchers keep track of the progression of their disease.

In both of these studies, researchers will look for clues in the strain of bacteria, the patient’s immune response, and lifestyle factors to see if they can find patterns that help account for the worse outcomes for African Americans. If certain strains or immune responses are more likely to lead to stomach cancer, that information could be used to identify patients who need H. pylori screening and treatment.

“For a rare cancer like stomach cancer, it’s better to identify which patients are at highest risk and then focus our preventive efforts on those patients,” Garman says. “It doesn’t make sense to apply screening to a large population for a cancer that’s rare.”

As a clinician, Garman is also excited to generate data that will inform guidelines to help her and her colleagues manage patients who have certain types of tissue damage that sometimes, but not always, lead to stomach cancer. Right now, there’s no way to know which of these people need more aggressive treatment and which simply need to be monitored.

Patierno, who has worked in cancer disparities for decades, says that the COVID-19 pandemic is shining a spotlight on health disparities in a way that adds new urgency to all of this work. “We’re right at the apex of changing the world right now,” he says, “mitigating cancer disparities with the goal of achieving health equity.”
 

This article appeared in the Winter 2021 issue of Breakthroughs magazine. Breakthroughs is produced twice yearly by Duke Cancer Institute Office of Development.