Key risk factors for the relative and absolute 5-year risk of cancer to enhance cancer screening and prevention.

BACKGROUND: This study identifies populations who may benefit most from expanded cancer screening. METHODS: Two American Cancer Society prospective cohort studies, Cancer Prevention Study-II Nutrition Cohort and Cancer Prevention Study-3, were used to identify the risk factors associated with a > 2% absolute risk of any cancer within 5 years. In total, 429,991 participants with no prior personal history of cancer were followed for cancer for up to 5 years. Multivariable Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for association. By using these hazard ratios, individualized coherent absolute risk estimation was used to calculate absolute risks by age. RESULTS: Overall, 15,226 invasive cancers were diagnosed among participants within 5 years of enrollment. The multivariable-adjusted relative risk of any cancer was strongest for current smokers compared with never-smokers. In men, alcohol intake, family history of cancer, red meat consumption, and physical inactivity were also associated with risk (p < .05). In women, body mass index, type 2 diabetes, hysterectomy, parity, family history of cancer, hypertension, tubal ligation, and physical inactivity were associated (p < .05). The absolute 5-year risk exceeded 2% among nearly all participants older than 50 years and among some participants younger than 50 years, including current or former smokers (<30 years since quitting) and long-term nonsmokers with a body mass index >25 kg/m2 or a first-degree family history of cancer. The absolute 5-year risk was as high as 29% in men and 25% in women. CONCLUSIONS: Older age and smoking were the two most important risk factors associated with the relative and absolute 5-year risk of developing any cancer.

The American Cancer Society's Cancer Prevention Study 3 (CPS-3): Recruitment, study design, and baseline characteristics.

BACKGROUND: Prospective cohort studies contribute importantly to understanding the role of lifestyle, genetic, and other factors in chronic disease etiology. METHODS: The American Cancer Society (ACS) recruited a new prospective cohort study, Cancer Prevention Study 3 (CPS-3), between 2006 and 2013 from 35 states and Puerto Rico. Enrollment took place primarily at ACS community events and at community enrollment "drives." At enrollment sites, participants completed a brief survey that included an informed consent, identifying information necessary for follow-up, and key exposure information. They also provided a waist measure and a nonfasting blood sample. Most participants also completed a more comprehensive baseline survey at home that included extensive medical, lifestyle, and other information. Participants will be followed for incident cancers through linkage with state cancer registries and for cause-specific mortality through linkage with the National Death Index. RESULTS: In total, 303,682 participants were enrolled. Of these, 254,650 completed the baseline survey and are considered "fully" enrolled; they will be sent repeat surveys periodically for at least the next 20 years to update exposure information. The remaining participants (n = 49,032) will not be asked to update exposure information but will be followed for outcomes. Twenty-three percent of participants were men, 17.3% reported a race or ethnicity other than "white," and the median age at enrollment was 47 years. CONCLUSIONS: CPS-3 will be a valuable resource for studies of cancer and other outcomes because of its size; its diversity with respect to age, ethnicity, and geography; and the availability of blood samples and detailed questionnaire information collected over time. Cancer 2017;123:2014-2024. © 2017 American Cancer Society.