Skip to Main Content
An official website of the United States government
Epidemiology and Genomics Research Program

Cancer Prevention Studies (CPS I, CPS II, CPS III, & CPS II Nutrition Cohort)

Lead Contacts and/or Principal Investigators (PIs):

Funded Since: 1959 (CPS I), 1982 (CPS II), 1992 (CPS II Nutrition Cohort)
Funding Source: American Cancer Society
Year(s) of Enrollment: as above
Study Website: Web Site Policy

In 1952, the Statistical Research Section, forerunner of the present Department of Epidemiology and Surveillance Research, began its first large prospective cohort study, the Hammond-Horn Study, to study the effect of cigarette smoking on death rates from cancer and other diseases. By using 22,000 American Cancer Society (ACS) volunteers to recruit a cohort of 188,000 adult men and then to trace cohort members yearly through 1955, that study set the methodologic foundation for the two subsequent Cancer Prevention Studies (CPS I and CPS II). In contrast to the Hammond-Horn Study, both CPS I and CPS II were designed to address a wide range of potential exposures, in addition to tobacco use, that may be associated with cancer. CPS I included approximately one million men and women recruited by 68,000 volunteers in 25 states. Participants were followed for 12 years, through 1972. CPS I data continue to be analyzed today, often in collaboration with external investigators, or to compare with results from CPS II, a separate and more contemporary cohort. CPS II began in 1982 and encompassed 1.2 million subjects recruited by 77,000 volunteers in 50 states. The entire CPS II cohort continues to be followed for mortality. Cancer incidence follow-up is being conducted in The CPS II Nutrition cohort, a subgroup of 184,000 men and women who completed a second questionnaire in 1992. A total of five follow-up questionnaires have been administered every two years to obtain updated exposure information and self-reported cancer diagnoses.

Early contributions from CPS II primarily involved tobacco research. The increase in lung cancer risk among male and female smokers in CPS II, compared to smokers in CPS I, was highlighted by a 1989 U.S. Surgeon General's Report and a 1997 NCI Monograph. CPS II provides the relative risk estimates from smoking used by the Centers for Disease Control and Prevention (CDC) to estimate deaths attributable to smoking in the United States. More recently, CPS II publications have contributed to our understanding of how various medications, medical conditions, familial, and environmental factors may affect cancer risk. CPS II data stimulated research interest and funding regarding the potential of aspirin-like drugs to inhibit colorectal cancer. The relationship between postmenopausal hormone replacement in women and mortality from cancers of the colon, breast, and ovary has been examined in eight publications. A CPS II publication on obesity and early mortality showed that the optimal range of body mass index remains constant throughout life, rather than increasing with age. Medical conditions associated with increased risk of various cancers include diabetes (pancreatic and colon cancer), infertility (ovarian), non-melanoma skin cancer (several), and hypertension or antihypertensive medications (renal cancer), but not spontaneous abortion (breast cancer). The Department has made notable contributions to research on environmental factors such as air pollution. The 1995 analysis with Dr. Arden Pope and other air pollution researchers at Harvard found increased death rates from cardiopulmonary conditions among CPS II participants living in cities with higher particulate air pollution. Together with the Harvard Six Cities Study, this finding motivated the Environmental Protection Agency (EPA) to propose more stringent limits on particulate air pollution.