ACS launches huge epidemiological study into causes of cancer
■ Previous efforts have confirmed links between cancer, smoking and obesity. Experts have great hopes for what they may find this time.
By Victoria Stagg Elliott — Posted May 28, 2007
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The American Cancer Society started recruiting a half-million subjects last month for Cancer Prevention Study-3.
This large, population-based prospective research project will use periodic questionnaires and blood tests to determine the lifestyle, genetic and environmental factors that make this disease more or less likely. It also will investigate how the interaction of these factors comes into play.
The society's first attempt at answering such questions was launched in 1959, when a million men and women were enrolled in a study that lasted until 1972. The results confirmed the association between tobacco use and lung cancer.
Researchers in the second effort, which is ongoing, have followed 1.2 million volunteers since 1982. These findings have shown that obesity increases the risk of several cancers and that aspirin use results in a lower death rate from colon cancer.
"While science can do a lot to explain the biology and genetics of cancer, some of the most valuable information we have is a direct result of the contributions of dedicated individuals over several generations," said Eugenia E. Calle, PhD, principal investigator and the ACS managing director of analytic epidemiology. "We are once again looking to the dedication, compassion and generosity of Americans to come through and help us provide answers that we know will save lives."
Researchers felt that there was a need for this latest project because of changes in lifestyle that mean that possible carcinogenic exposures are different from previous generations. For instance, people take more medications now, and this circumstance is one of many about which researchers will ask. "We need to compare the exposures of the times, and that's very difficult to do when you don't have a new group of younger people," Dr. Calle said.
Improvements in technology also will allow for a better understanding of cancer's genetic underpinnings. To take advantage of this, participants will give blood samples from the get-go, something that wasn't done at all in the first study and only for a proportion of those in the second.
"There are lots of things we can do with blood samples to complement what we get from a questionnaire," Dr. Calle said.
Many single genes that confer a very high risk of cancer already have been discovered. The hope is that this undertaking will allow those that aren't quite so powerful, but still have an influence, to be found.
"It's very exciting and important research, but it's not going to be a simple story. We are not going to find one or two genes. We are going to see genetic patterns that give a person a somewhat higher risk," said ACS President Richard C. Wender, MD.
The first recruitment efforts will take place at ACS "Relay for Life" fundraisers over the next year, although there are plans to expand the target population beyond these events, because including as diverse a population as possible is also one of this project's goals.
"We are very committed to having ethnic and racial diversity in this study," said Dr. Wender, who has signed himself up and is the alumni professor and chair of the Dept. of Family and Community Medicine at the Jefferson Medical College of Thomas Jefferson University in Philadelphia.
Physicians praised the effort because, despite advances in screening and treatment, the development of new preventive strategies is viewed as the most likely means to further decrease cancer death rates. These numbers have been declining since the early 1990s, although cancer incidence has been stable.
"Cancer is something that affects an enormous amount of humanity. We have seen the benefits of prevention in regards to cardiovascular disease. I would like to see that in cancer," said Therese Bevers, MD, medical director of the cancer prevention center at the University of Texas MD Anderson Cancer Center in Houston.