Analyses of SEER data on overall (not stage-specific) incidence rates have shown increases for ER+ versus declines for ER− breast cancers (including age 30–49 years), and these divergent trends are unexplained [28]; the limitations of hormone-receptor data from cancer registries must be acknowledged, including missing data and temporal changes in sensitivity of tests [28]. This evidence concerns the gene ESR1 and breast carcinoma.