Breast Cancer Incidence Rates Vary by Region in U.S. Women Younger Than 40

Feb 28, 2025

THURSDAY, Feb. 27, 2025 (HealthDay News) — For U.S. women younger than 40 years, breast cancer incidence rates vary by geography, according to a study published online Feb. 12 in Cancer Causes & Control.

Rebecca D. Kehm, Ph.D., from Columbia University in New York City, and colleagues analyzed age-adjusted breast cancer incidence rates from 2001 to 2020 in women aged 25 to 39 years using the U.S. Cancer Statistics database. The average annual percentage change (AAPC) was calculated using Joinpoint regression.

The researchers found that in 21 states, breast cancer incidence increased by more than 0.50 percent per year in women younger than 40 years from 2001 to 2020, while incidence remained stable or decreased in other states. Compared with the five states with the lowest rates, incidence was 32 percent higher in the five states with the highest rates. Despite having the lowest absolute incidence rate from 2001 to 2020, the Western region had the highest rate of increase (AAPC, 0.76). Among women aged younger than 40 years, the highest absolute rate of breast cancer was seen in the Northeast, with a significant increase seen over time (AAPC, 0.59). The only region where breast cancer in women younger than 40 years did not increase from 2001 to 2020 was the South.

“Incorporating place-based factors, along with other established risk factors, into risk prediction may enhance our ability to identify groups of younger women who are at higher risk for early-onset breast cancer,” the authors write. “This, in turn, can inform targeted strategies for risk reduction, screening, and broader policy and community-based efforts to mitigate the rising rates.”

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