The American Cancer Society has advised for decades against tobacco smoking and sedentary lifestyles. It has long encouraged healthy eating habits as part of its cancer prevention efforts. While the latest long-term prevention study by the ACS, called the Cancer Prevention Study 3 or CPS-3, also looks at lifestyle choices like diet and exercise, it holds the promise of discovering more answers to environmental causes of cancer.
The landmark CPS-3 aims to include 300,000 Americans and yield new answers to explain why some of us get cancer and others do not. I asked ACS Senior Epidemiologist Lauren Teras, PhD this question about environmental toxins: "To what extent does the CPS-3 study follow the recommendations of the President's Cancer Panel of medical experts calling for a closer look at environmental toxins? (quote from 2008-2009 PCP report: 'the true burden of environmentally induced cancers has been grossly underestimated.') "
Teras answered, "Environmental toxins are among the very important exposures we hope to study in CPS-3. Through linkage with publicly available data (e.g. from EPA monitoring stations) and through measurements taken in the blood, we have several ways we will be able to tackle the question of how these toxins may impact risk of cancer." The study also asks participants about their place of work.
I asked if the CPS-3 would be looking at cancer clusters. Teras explained, "This study is limited by the population of people who choose to enroll. We will not have comprehensive coverage of all cancer cases in a geographic area. However, since we do have addresses for our participants we are able to study residential proximity to exposures such as environmental pollutants and subsequent cancer development in our cohort."
When I asked Teras to clarify what is meant by "environmental" exposures in the CPS-3, she responded. "People do tend to use the term "environmental" to mean both pollutants and lifestyle factors like obesity and smoking. We are interested in all of the above but that absolutely includes traditional environmental toxins (e.g. contaminants in air, water, soil, etc...)."
Teras further explained that blood samples will be used to compare selected substances in the blood of people diagnosed with cancer against others not diagnosed with cancer. The timetable for scientists drawing any conclusions from this long-term study is a long one, ranging from a few years to even longer. We can watch for results and guidelines stemming from CPS-3 at the cancer.org website of the ACS.
Tomorrow: why a cancer prevention group says more should be done now!