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

Abstract

U.S. cancer screening guidelines recommend that cancer screening begin for breast cancer at age 40 and for colorectal cancer and prostate cancers at age 50. What are the marginal returns to physician and individual compliance with these cancer screening guidelines? We estimate the marginal benefits by comparing cancer test and cancer detection rates on either side of recommended initiation ages (age 40 for breast cancer, age 50 for colorectal and prostate cancers). Using a regression discontinuity design and self-reported test data from national health surveys, we find test rates for breast, colorectal, and prostate cancer increase at the guideline age thresholds by 78%, 65% and 4%, respectively. Data from cancer registries in twelve U.S. states indicate that cancer detection rates increase at the same thresholds by 25%, 27% and 17%, respectively. We estimate statistically significant effects of screening on breast cancer detection (1.3 cases/1000 screened) at age 40 and colorectal cancer detection (1.8 cases/1000 individuals screened) at age 50. We do not find a statistically significant effect of prostate cancer screening on prostate cancer detection. Fifty and 65 percent of the increases in breast and colorectal case detection, respectively, occur among middle-stage cancers (localized and regional) with the remainder among early-stage (in-situ). Our analysis suggests that the cost of detecting an asymptomatic case of breast cancer at age 40 is approximately $100,000-125,000 and that the cost of detecting an asymptomatic case of colorectal cancer at age 50 is approximately $306,000-313,000. We also find suggestive evidence of mortality benefits due to the increase in U.S. breast cancer screening at age 40 and colorectal cancer screening at age 50.