This month, the Cancer Prevention Study 3 (CPS-3) begins evaluating 300,000 volunteer participants to observe their lifestyle habits and behaviors over the course of 20 years or more.1

Conducted by the American Cancer Society, CPS-3 has been designed to gather data about the environments and lifestyles of people who may or may not develop cancer during two decades of clinical observation.

Dr. Alpa Patel, the strategic director of this study, said important information will begin to arrive within the first 5 years of the study. Oncologists will not have to wait for results to appear at the end of the 20-year study cycle, she noted. Instead, the medical community can look forward to results of the study being released when new insight into what causes cancer is brought to light. 

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“We are already beginning research as we begin recruitment,” said Dr. Patel, also adding that CPS-3 will begin delivering actionable data much more quickly than the previous studies, CPS-1 and CPS-2. CPS-1 focused on following smokers in relation to cancer,2 while CPS-2 concentrated on the impact of obesity in relation to the disease.3

However, CPS-3 aims to look at a broader set of lifestyle factors in an effort to identify potential behavior that might trigger the development of cancer, said Dr. Patel. While activities such as smoking and drug use will be followed, as will obesity trends, CPS-3 will go even further, studying the correlations between the appearance of cancer and a range of behavior and lifestyle scenarios, including (but not limited to) lack of exercise, marital status, and pet ownership.

“The beauty of this study is that it is very wide and multifaceted,” said Dr. Patel. “We are following patients for all types of cancer. We are looking for things we don’t yet know about, as well as how different factors affect the risk of developing cancers.”

The Method Behind CPS-3 

A recent recruitment period for the study took place in San Francisco, CA, in early August, with a focus on recruiting gay, lesbian, and transgender volunteers into the study.4 Recruitment in these categories is important because gay men are twice as likely to smoke as heterosexual men, and lesbian women have been identified as having a greater risk for cancer due to smoking, obesity, and not having children.

The first 5 years of the study will begin to reveal data about behavior and lifestyles in relation to the occurrence of the most common forms of cancer, said Dr. Patel. The cancers that Dr. Patel expects to see first are breast, colon, prostate, and lung. Instances of ovarian cancer, skin cancer, lymphoma, or other forms of cancer, she said, will likely appear later in the study.

The methodology of CPS-3 roughly follows the methodology of CPS-1 and CPS-2, said Dr. Patel. Participants are between the ages of 30 and 65 years with no previous diagnosis of cancer are selected. As part of the study, they are asked to provide information on their lifestyle and behavior. Subsequently, the participants are contacted occasionally for updates on their behavior—including their weight gain based on the measurement of their midsection—and asked if they have been diagnosed with cancer. But considering that participants may not always provide an honest answer, what is the margin of error for these studies?

Dr. Mia Gaudet, the director of genetic epidemiology for the American Cancer Society was the principal research lead on the CPS-2 study of obesity and its correlation with cancer. “Participants are very honest in general,” said Dr. Gaudet. “They are not being paid to participate, but up to 85% of participants in CPS-2 still respond to questionnaires and newsletters.”

Impact on the Study Participant’s Lifestyle

Does participating in a cancer study potentially increase the onset of cancer in a study participant due to the stress or anxiety of participation? “It’s a good, but difficult question,” said Dr. Gaudet. “Stress is always a factor in disease.” Dr. Patel agrees, and is prepared to factor in the stress of participation in CPS-3.

“If you think about it,” she said, “CPS-1 didn’t say to participants ‘smoking is bad for you.’ It simply conducted a study on smokers. Even the authors of the study, Hammond and Horn, were smokers. So you have to understand that what’s happening in the lab is different from that which happens in the regular environment. That means the task of the study is to translate findings into the larger population.”

Study participants are not instructed to do anything but tell the truth about their behavior and their medical condition. “They are given no medications, are not divided into test and control groups, and are simply asked to behave the way they want”, said Dr. Patel.

The relationship between personal behavior and being diagnosed with cancer plays a significant role in the creation of public policy, and CPS-3 will be looked upon by lawmakers as evidence for or against the wishes of their constituencies, she added.

“It’s proven that public guidelines are developed from these studies,” said Dr. Patel. “When we say eat less red meat, avoid tobacco smoke, all these things are developed into guidelines and, sometimes, regulations.”

What Results Will Find 

Study results from CPS-3 could potentially help prevent cancer as well, said Dr. Patel. “It’s important for [healthcare professionals] to understand lifestyle effects on their patients before they are potentially diagnosed with cancer. They want to be able to tell patients what they need to be doing as far as lifestyle changes in order to stay alive.”

Study results will be developed and published according to specific types of cancer, said Angie Carrillo, a spokesperson for the American Cancer Society. “What’s important about CPS-3 is that it doesn’t share the specific intent of CPS-1 and CPS-2. It’s much broader, it’s much less contained. We want to learn a great deal more about what conditions cause cancer,” she said.

If you or your patients are interested in participating in the CPS-3 study, visit for details.


1. American Cancer Society (2013). Enrollment website. Accessed at

2. American Cancer Society (2013) How the Cancer Prevention Studies Save Lives. Accessed at

3. American Cancer Society (2013) Cancer Prevention Study II (CPS II). Accessed at

4. American Cancer Society – California LGBT Team site. Accessed at