April 4, 2003

Southern Community Cohort Study on track

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William Blot, Ph.D.

Southern Community Cohort Study on track

After nearly a year of recruitment, the Southern Community Cohort Study (SCCS) is on track with an encouraging proportion of enrollees agreeing to give biologic samples and successful efforts to recruit men and African-Americans.

The SCCS is a National Cancer Institute-funded study that aims to understand and address racial, ethnic and regional disparities in cancer incidence and mortality. It is historic because it is the largest population-based health study of African-Americans ever conducted. It also offers tremendous potential to provide important insight about other major diseases, including heart disease and diabetes.

The SCCS is a collaborative effort of the Vanderbilt-Ingram Cancer Center, Meharry Medical College, both in Nashville, and International Epidemiology Institute, based in Rockville, Md.

The team leading the landmark initiative, including co-principal investigators William Blot, Ph.D., of Vanderbilt-Ingram and IEI, and Margaret Hargreaves, Ph.D., of Meharry, reported its progress recently to the study’s Scientific Advisory Board.

Among the specifics that the board heard:

• As of the end of February, more than 11,000 individuals had been enrolled. The study ultimately will enroll 105,000 people, two-thirds of them African-Americans, to identify genetic, environmental and lifestyle factors that contribute to cancer.

• 13 federally funded community health centers (CHC) throughout the Southeast were actively participating in the study in mid-March when the progress report was presented. An additional seven CHCs began enrollment by the end of March, with an eighth site expected to enter the study later this year. The addition of so many new CHCs into the study is expected to provide another substantial boost in enrollment, investigators said.

• 93 percent of all participants — and 99 percent of eligible participants — have agreed to provide blood or saliva samples in addition to answering a detailed health and lifestyle questionnaire and agreeing to be followed for many years. The biologic samples are an optional part of the study, and investigators have been surprised that so many participants have agreed to donate.

• 44 percent of the enrolled participants are men, and 80 percent are African-American. “Because both these proportions are larger than the overall patient population at the CHCs, this reflects success thus far in attracting men and African-Americans into the study,” Blot told the advisory board members.

• Education level is low, with one-third having completed less than 12 years of school, one-third having graduated high school and one-third with some level of education beyond high school.

• Household income is also low, with 60 percent earning less than $15,000 per year.

• The median age of participants at entry into the cohort is about 50. The study targets patients ages 40-79.

The study focuses on African-Americans and residents of the Southeast — Tennessee, Mississippi, Georgia, South Carolina, Alabama and Florida — because their rates of cancer incidence and mortality are higher than other groups. The study is expected to provide insights into how better to indentify the causes of and prevent cancer and other major health problems among these groups as well as other ethnic and regional populations.

The NCI has provided more than $22 million to fund the initial five years of the study; however, Vanderbilt-Ingram is working to raise an additional $6 million to pay for expenses that the NCI grant will not cover.

Cohort studies such as this one enroll large numbers of people and track them over many years for subsequent development of disease. Such studies have yielded much of what is known about the cause and prevention of diseases like cancer.

Some of the better known cohort studies include the Framingham Heart Study, the Harvard Nurses and Physicians studies and the American Cancer Society cohort study. However, these existing studies do not include sizeable proportions of African-Americans, low-income participants, and, with the exception of an Iowa-based cohort of women, rural residents.

The study involves a survey of lifestyle and health information, follow-up contact every other year, and the optional collection of blood and saliva samples. These samples will provide an invaluable resource for future DNA testing as new genes and proteins are identified and new technologies are developed to identify “markers” of disease risk. Future studies using these specimens could have far-reaching implications for years to come.

The SCCS’ Scientific Advisory Board includes Dr. Brian Henderson of the University of Southern California; Dr. Clark Heath, retired from the American Cancer Society; Dr. Funmi Olepade of the University of Chicago; Dr. Louis Sullivan of Morehouse School of Medicine; and Dr. Walter Willett of Harvard University.

For more information about the study, visit www.southerncommunitystudy.org.