Though the connection between smoking and cancer may now seem like a given, it was only uncovered after many years of research. These field-changing studies are continuing today.
We take much of our current knowledge about cancer risk for granted. Kick the cigarette habit - reduce your cancer risk. Maintain a healthy weight - reduce your cancer risk. Eat a balanced diet - reduce your cancer risk. However, this information was not always known, and in the fairly recent past, we were blind to these ways of reducing the risk of cancer.
Much of what is known about cancer risk was uncovered in large, long-term studies, requiring dedication from huge numbers of participants and researchers alike.
As the newest such study, called the Cancer Prevention Study-3 (CPS-3), gears up, many are looking back to see just what these studies have taught us over the years.
In an interview with dailyRx News, Alpa V. Patel, PhD, Strategic Director of CPS-3, shed some light on what we have learned in previous studies, and what researchers hope to uncover moving forward with the newest project.
Long-Term Cancer Research Revealed
The American Cancer Society (ACS) began its long-term cancer studies, called Cancer Prevention Studies (CPS), during the 1950s. These studies gather baseline information from participants, including lifestyle, medical and behavioral data, and then follow the participants over time, monitoring their health and looking for connections.
According to ACS, this research has played a major role in understanding cancer and improving cancer prevention.
"More than 300 scientific articles by American Cancer Society epidemiologists have been published from these studies and findings have significantly contributed to tobacco-related research, and to the understanding of obesity, diet, physical activity, hormone use, air pollution, and various other exposures in relation to cancer and other diseases," reported ACS.
In an interview with dailyRx News, Marlene M. von Friederichs-Fitzwater, PhD, MPH, director of the Comprehensive Cancer Center Outreach Research and Education Program at the University of California, Davis, highlighted the important role of CPS in the cancer field.
"Cancer prevention studies are extremely important in order to better understand the risk factors for different types of cancer and among different populations," said Dr. von Friederichs-Fitzwater. "For example, the American Cancer Society's study of individual self-reported behaviors over several years has provided knowledge about dietary risks as well as dietary benefits relevant to cancer and more information about environmental issues."
Dr. von Friederichs-Fitzwater added, "We need to do more to prevent cancer and to reduce cancer health disparities, and cancer prevention studies provide valuable information."
What We've Learned Already
The initial CPS began with the Hammond-Horn Study, executed from 1952 to 1955. This study of 188,000 American men was the first study of its size to explore cigarette smoking and death from cancer or other diseases.
"Hammond-Horn provided the first evidence towards the collective scientific basis for all of the tobacco control and public health policies in place," said Dr. Patel, who pointed out that it is also the basis for policies aiming to protect against secondhand smoke exposure.
This translates to tens of hundreds of thousands of lives saved, Dr. Patel told dailyRx News.
"About half of men smoked when the Hammond-Horn study started. Just around 20 percent of adult men smoke today," said Dr. Patel.
The Hammond-Horn Study was followed up with the CPS-1, which started in 1959 and ended in 1972. This study involved approximately one million subjects (men and women) from 25 different states. This study widened the focus from just cigarette smoke to other possible exposures that might have an effect — positive or negative — on cancer risk.
Though CPS-1 made great strides, cancer research would continue to widen. "That particular population was only followed for what they died of," said Dr. Patel of CPS-1. "Back then, the vast majority of individuals with a cancer diagnosis did not survive that diagnosis."
The next study, CPS-II, was started in 1982 and is still ongoing today. This study includes 1.2 million subjects from all 50 states, the District of Columbia and Puerto Rico. "Like CPS-I, this study was designed to address a wide range of environmental and lifestyle exposures that may increase or decrease cancer risk," explained ACS.
According to Dr. Patel, CPS-II broke open the field by studying the link between obesity and cancer.
A Nutrition Cohort of this CPS-II study was started in 1992 and includes 185,000 subjects from 21 states. The focus of this cohort is to further explore the connection between diet and cancer risk.
However, the CPS-II population is aging, and a new study — CPS-3 — is getting started.
CPS-3: A New Generation
The CPS-3 will follow a new generation of participants for 20 to 30 years, and hopefully, provide insight on environmental and lifestyle changes not seen in earlier CPS studies.
"We live differently today," said Dr. Patel. "The average age of the CPS-2 population is now 80 years old. We now have a new generation that takes different kinds of medications, that has higher rates of obesity and is more sedentary because of technological advancements and greater dependence on cars, among many other things.
"How all of these different emerging or evolving factors affect cancer risk is yet to be understood. And that's why a new generational study is needed," explained Dr. Patel.
The ACS has enrolled its initial group of 300,000 ethnically and racially diverse adults from all over America. Subjects include men and women between the ages of 30 and 65 with no personal history of cancer (not including basal or squamous cell skin cancer).
"This younger study population will have environmental and lifestyle exposures that may be meaningfully different from our previous populations and will help us further advance our understanding of the factors that cause or prevent cancer," explained ACS.
Dr. Patel explained that a wide range of information will be gathered from the participants, including surveys, physical measurements like waist circumference and a blood sample. Every two to three years, the participants will complete a follow-up survey to update topics that might change, like lifestyle behaviors, medication use, use of tobacco products, diet, physical activity levels and so on.
Because the participants will be surveyed every few years over many years, the researchers have the opportunity to introduce new questions that might arise with every survey. "We can continually enrich the data," said Dr. Patel.
Though the researchers behind CPS-3 have some key areas in mind, the studies are intentionally built to have multiple focuses, said Dr. Patel.
"We know that we will continue work in the areas of tobacco and obesity, but there are things we may not know today because the technology does not yet exist, but with advancements, we are prepared to answer those questions tomorrow." Dr. Patel told dailyRx News.
For Dr. Patel, though the particular focuses might change and develop over time, the broad aim of CPS-3 is clear and twofold.
"Our ultimate goal is to better understand what causes cancer to develop and what causes cancer to progress so that we can understand where and how we might be able to reduce the amount of cancer that develops," said Dr. Patel.
The second goal? Enhancing survival rates and lengthening the lives of those who do develop cancer.
ACS has high hopes for what CPS-3 might mean for the field of cancer prevention.
"Through this landmark new study, we will continue our work to eliminate cancer as a major health concern for future generations and create a world with more birthdays," said ACS.