EARLY-onset breast cancer incidence in the U.S. is rising, but new research suggests the increase is not uniform across all states. A recent study analyzing trends from 2001 to 2020 found that breast cancer rates in women under 40 have increased significantly in 21 states, with distinct regional differences.
Using data from the U.S. Cancer Statistics database, researchers identified that incidence was 32% higher in the five states with the highest rates compared to the five states with the lowest. The Western region, despite historically having the lowest breast cancer incidence in young women, showed the fastest increase (average annual percent change [AAPC] = 0.76, 95% CI 0.56–0.96). The Northeast had both the highest absolute incidence rate and a significant upward trend (AAPC = 0.59, 95% CI 0.36–0.82). Meanwhile, the South was the only region where early-onset breast cancer rates remained stable over the 20-year period.
These findings suggest that place-based exposures may contribute to breast cancer risk in younger women, potentially offering new insights for early detection and prevention strategies. The study authors propose that incorporating geographic risk factors into breast cancer prediction models—alongside genetic and lifestyle factors—could improve risk assessment and early intervention efforts.
Given the growing incidence in specific regions, healthcare professionals may need to consider geographic context when assessing patient risk. Further research is required to determine the environmental, socioeconomic, or healthcare access factors that might drive these regional disparities.
Reference: Kehm RD et al. Geographic differences in early-onset breast cancer incidence trends in the USA, 2001–2020, is it time for a geographic risk score?. Cancer Causes Control. 2025. doi:10.1007/s10552-025-01968-7.
