How Effective is Population-Based Cancer Screening? Regression Discontinuity Estimates from the US Guideline Screening Initiation Ages

We estimate the marginal benefits of population-based cancer screening by comparing cancer test and detection rates on either side of US guideline-recommended initiation ages (age 40 for breast cancer and age 50 for colorectal cancer during the study period). Using a regression discontinuity design and self-reported test data from national health surveys, we find test rates for breast and colorectal cancer increase at the guideline age thresholds by 109% and 78%, respectively. Data from cancer registries in twelve US states indicate that cancer detection rates increase at the same thresholds by 50% and 49%, respectively. We estimate significant effects of screening on earlier breast cancer detection (1.2 cases/1000 screened) at age 40 and colorectal cancer detection (1.1 cases/1000 individuals screened) at age 50. Forty-eight and 73% of the increases in breast and colorectal case detection occur among middle-stage cancers (localized and regional) with most of the remainder among early-stage (in-situ). Our analysis suggests that the cost of detecting an asymptomatic case of breast cancer at age 40 via population-based screening is $107,000–134,000 and that the cost of detecting an asymptomatic case of colorectal cancer at age 50 is $473,000–485,000.