Researchers from Washington University in St. Louis utilized SEER registries to conduct their analyses. SEER is a public database from the National Cancer Institute with coverage of 27% of the US population, and a long-track record of statistical backbone to translate the data from SEER to numbers that are representative of the population at large.
From 2000 to 2019, more than 200,000 young women were diagnosed with primary invasive breast cancer in the dataset, and I’ve already given you the top-line results. Of course, when you see a graph like this the next question really needs to be “why”?