No large studies have ever been done on colon cancer in blacks, however, to find out why.
Now, with the help of a four-year, $2.6 million National Cancer Institute grant, researchers at the University of North Carolina at Chapel Hill schools of medicine and public health are launching what they believe is the first major investigation of the illness in both races. Thirty-three central and eastern N.C. counties, almost 50 hospitals, 800 colon cancer patients and 800 healthy control subjects will be involved.
"We have a lot of questions we hope to answer," said Dr. Robert S. Sandler, professor of medicine at UNC-CH and principal investigator. "When people move from a low-incidence area such as Africa or Japan to a high-incidence area such as the United States, the disease rates go up. That strongly suggests that something in the environment rather than simply genetics is responsible.".
Since diet and lifestyles tend to change dramatically when people move from one continent to another, researchers want to find what elements of American diets and other activities could promote cancer. They also will investigate differences in the ability to metabolize compounds in foods.
Cancer screening opportunities, access to health care, attitudes about medicine and social factors also will be studied and compared.
"For us to come up with valid, useful answers we need as many eligible people as possible to participate," Sandler said. "After getting permission from their physicians, we will contact patients we have identified through the central cancer registry first by mail and then by telephone seeking their cooperation."
Researchers also will contact people without colon cancer for comparison. All subjects will be given personalized dietary recommendations and $25 cash for allowing a nurse to visit them at home and completing a confidential questionnaire with the nurse's help.
"One of the strengths of our study will be that we will be able to look at and carefully analyze a comprehensive list of different factors such as diet and physical activity in such a large group," Sandler said. "Among other benefits, it is an opportunity for people in the black community to help one another by helping us learn why blacks in this country are at greater risk of dying from colon cancer than whites."
Each year, doctors diagnose about 140,000 new colon cancer cases in the United States, and about 50,000 deaths occur, said Sandler, a member of the UNC Lineberger Comprehensive Cancer Center. Between 1973 and 1991, the death rate for the illness fell 17.6 percent among whites and increased 12.4 percent among blacks.
Others involved in the study include Drs. Robert C. Millikan and Beth M. Newman of epidemiology, Alice S. Ammerman of nutrition, John T. Woosley of pathology, Lawrence Kupper of biostatistics and Richard A. Rippe of medicine, all at UNC-CH.
Note: Sandler can be reached at (919) 966-8138.