The American Cancer Society began its third major long-term follow-up study in 1982, enrolling approximately 1.2 million American men and women. This nationwide study, called Cancer Prevention Study II (CPS-II) – and its companion study, the CPS-II Nutrition Cohort – have yielded mountains of cancer insights – including numerous breast cancer insights.
By following initially cancer-free adults for many years, Society researchers are able to closely track who gets cancer and then can work to figure out why. They do this by analyzing the information (such as weight or eating habits) and biospecimens that participants provided (such as blood and DNA samples) to figure out possible lifestyle, medical, environmental and biologic factors that contribute to a higher risk of developing the disease.
CPS-II data have – and continue to – shed light on some of the major potential causes and pathways to prevention of breast cancer in particular. The following are 5 key findings about breast cancer from CPS-II:
1. Walking helps women lower their risk of breast cancer: A CPS-II analysis of more than 73,000 post-menopausal women found that those who walked at least 7 hours per week were 14% less likely to develop breast cancer after menopause.
2. Losing weight and keeping it off could reduce breast cancer risk: An analysis of data from the CPS-II Nutrition Cohort suggests that losing 10 or more pounds and keeping it off for at least 5 years might reduce breast cancer risk among postmenopausal women.
3. Gaining weight significantly increases the likelihood of developing breast cancer: A study of women from CPS-II has shown that those who put on 60 or more pounds after age 18 double their risk of a post-menopausal breast cancer diagnosis.
4. Smoking may increase risk of breast cancer for women: A study of women from CPS-II suggested that those who smoke – especially those who drink alcohol and smoke – are at increased risk for developing breast cancer. Additionally, women who started smoking at an earlier age were at an even higher risk for breast cancer.
5. Understanding common genetic variations may help to predict breast cancer risk: CPS-II data and biospecimens have been used as part of a larger collaborative study that has enabled researchers to identify or confirm most of the common genetic variants associated with increased risk of breast cancer in women. The more genetic variations linked to breast cancer that scientists find, the more useful the information will be for understanding why some women are at high-risk of getting the disease.