The science of large numbers pg. 3
Researchers know that Asia and the United States have quite different cancer spectra. In China and Japan, stomach cancer used to be the number one culprit followed by cancer of the esophagus; whereas in the United States, lung, colon, and breast cancers dominate.
However, the cancer spectrum in some parts of China, such as Shanghai, is starting to more closely resemble that of the United States. For people who move from China to the United States, the risk of stomach and esophageal cancers decreases while the risk of lung, colon, and breast cancers dramatically increases.
The million-dollar question, of course, is “Why?”
One hypothesis is that lifestyle factors—including diet—account for these differences.
The Shanghai studies were designed to test the hypothesis that the traditional Asian diet, which includes soy foods, bok choy (Chinese cabbage), white radish, ginger root, tea and ginseng, may reduce the risk of diseases including some cancers.
To find out, the Shanghai studies rely on trained interviewers who go door-to-door. Because most Shanghai residents live in apartment towers, dozens of study participants can be found in one building. The interviews are later transferred from paper to an electronic form for data analysis.
“In-person interviews improve the quality of the data,” Zheng explains, “particularly across a large population with diverse educational and income backgrounds. If you asked someone to fill out a form, you may get different quantities and quality of responses. In-person interviews minimize the differences.
“Secondly, the response rate is high with in-person interviews. We have a 93 percent response rate. Mailed surveys typically get a 25 percent to 40 percent response.”
A higher response rate makes it easier to generalize findings across a population, he adds.
Empower the people
The Southern Community Cohort Study takes a different tack. Its researchers rely on community health centers to enroll study participants, most of whom are lower income.
Betty Scott, an interviewer at the West End Medical Centers in Atlanta, has enrolled over 2,600 people into the study. Her interest in the project is more than academic.
“I have a history of cancer in my family,” she explained in 2007, having lost her father, a brother, and a sister to cancer. Three other brothers have been diagnosed with cancer.
“Of course, I want to know what is causing so much disease,” Scott says. “We all have theories, but until research proves what is causing cancer, we will never know the answers.”
“A lot of folks in our area have been affected by cancer,” adds Emily Beauregard, who enrolled about 90 people a month in 2006 at the Family Health Centers’ Portland Clinic in Louisville, Ky.
“There’s not a lot one person can do to stop disease or make someone who has cancer better,” says Beauregard, who is currently enrolled in a master’s degree program in public health. “But if you can participate in something that may in the long run halt or decrease the rates of cancer, people feel that is empowering to be able to do something about it.”
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