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/m 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.