Invasive Breast Cancer Incidence Has Increased Among Young Women

Invasive breast cancer incidence among US women aged 20 to 49 years increased from 2000 to 2019, especially after 2016, according to research published in JAMA Network Open.

Researchers found that changes in incidence varied by race and hormone receptor status, which highlights “the need for further research into specific breast cancer risk factors among younger women and possible targeted breast cancer prevention strategies for at-risk groups.”

The study included 217,815 women with primary invasive breast cancer (from the SEER 17 registries). Patients were 20 to 49 years of age. Most (58.3%) were non-Hispanic White, 17.0% were Hispanic, 12.4% were non-Hispanic Black, 11.6% were Asian or Pacific Islander, and 0.7% were American Indian or Alaska Native. Most patients (61.5%) had estrogen receptor (ER)-positive/progesterone receptor (PR)-positive disease.

From 2000 to 2019, breast cancer incidence rates increased 0.79% per year. Incidence increased “gradually” between 2000 and 2016 (annual percentage change [APC], 0.24) and “dramatically” after 2016 (APC, 3.76), according to the researchers.

The highest age-standardized incidence rates (ASIRs) were seen in non-Hispanic Black patients (70.7 patients per 100,000) and non-Hispanic White patients (69.7 per 100,000). ASIRs were lowest in non-Hispanic American Indian or Alaska Native patients (52.6 patients per 100,000) and Hispanic patients (52.8 patients per 100,000).

In the youngest age groups, ASIRs were highest among non-Hispanic Black patients, who had an incidence rate ratio (IRR) of 1.53 at ages 20 to 29 and an IRR of 1.15 at ages 30 to 39.

Over the study period, the ASIR increased for ER-positive/PR-positive disease (average APC, 2.72) and ER-positive/PR-negative disease (average APC, 1.43), but the ASIR decreased for ER-negative/PR-positive disease (average APC, –3.25).

“These results suggest that understanding factors driving differential trends in incidence rates for different age groups by race and ER-positive status should provide insights into breast cancer prevention in young women,” the researchers wrote. 

This article originally appeared on Cancer Therapy Advisor