Gut check
By Alicia Di Rado
Humanity can learn much from the ties that unite it, but sometimes differences may teach far more, especially when it comes to medicine.
When scientists in the 1950s noticed that their study participants who smoked had more lung cancer and heart attacks than other participants, it foretold the risks of tobacco use. Later, researchers studying diets around the world noted that Mediterranean dwellers had less heart disease; eventually, that bolstered the importance of eating fruits, vegetables, nuts and certain oils.
City of Hope surgeon Joseph Kim, M.D., knows that even small health disparities can teach researchers a lot. Evidence hints that may be the case for diseases he knows well: gastrointestinal cancers.
As a gastrointestinal surgeon who has seen many Asian-American patients, Kim decided to investigate how well Asian-Americans do after treatment for stomach, colon, pancreatic, esophageal and liver cancers. He suspected statistics would show that they fared worse than other patients. After all, Asian-Americans are the only people in the United States hit harder by cancer than heart disease.
But what he and his multidisciplinary team discovered surprised him. Asian-Americans actually fare better than others. Far better.
Now researchers want to know whether factors such as diet or access to care are at play. They also wonder about genetic markers involved in these cancers. Scientists might use these genetic clues to focus on new targets for medication or to make treatment decisions — and that may help patients of many ethnicities.
STARTING IN THE STOMACH
Gastric or stomach cancer is the second-leading cancer worldwide and one of the top five causes of cancer death. Asians have the highest risk worldwide for this cancer, which is linked to infection with helicobacter pylori (the bacteria that cause ulcers) and consumption of salted and pickled foods, a staple of Asian diets.
Statistics also show that gastric cancer patients in Eastern nations are more than twice as likely as those in Western nations to survive for five years after diagnosis. Asian surgeons have attributed that success to how extensively they operate, but other studies debunked that theory. That got Kim wondering: If surgical technique cannot explain it, then could it be something about the Asian patients themselves?
City of Hope surgeons and epidemiologists looked to numbers for answers. They analyzed more than 13,500 cases of gastric cancer in Los Angeles County from 1988 to 2006. It is the largest study yet on racial disparities in gastric cancer.
They found that regardless of patients’ cancer stage or treatment, patients of Asian descent with gastric cancer lived longer. They survived nearly twice as long as Latinos, while blacks and whites fared worst.
Researchers shared their findings in January at an American Society of Clinical Oncology symposium.
COLON QUESTIONS
As it turns out, Kim said, results appear similar in colon cancer.
City of Hope scientists studied more than 78,000 patients with colon cancer, one of the most common cancers in the U.S., and again Asian- Americans seem to fare best, followed by Latinos.
“It’s not really clear why these differences exist, but it’s unlikely to be related to surgical technique,” Kim said. Instead, people of Asian descent might be more likely to have something in their genetic composition that makes tumors less aggressive or more amenable to treatment.
“Is it genetic? Are Asian patients more likely to get follow-up on their cancer? Does diet play a role? We just don’t know,” Kim said. But they will find out.
Kim and colleagues Julio Garcia- Aguilar, M.D., Ph.D., chair of the Department of Surgery, Alessio Pigazzi, M.D., Ph.D., professor of surgery, and Smita Bhatia, M.D., M.P.H., chair of the Department of Population Sciences, plan to launch a pilot study focusing on colon cancer. They intend to analyze cancer cells in City of Hope’s new tumor tissue repository to look for markers that may offer survival advantage.
In the future, they hope to monitor patients as they are diagnosed and follow them over time to get a fuller picture of the factors contributing to better outcomes. They also will expand on their studies of pancreatic, esophageal and liver cancers.
“We believe this research has the potential to make a difference,” Kim said. “We’re in the right place to do these studies. Los Angeles County is diverse and has a significant Asian population, and we have people who bring expertise from their disciplines to pursue solid scientific research in this area.”
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