# Rising Breast Cancer Incidence and Poor Outcomes in Young Women: A Retrospective Study

## TL;DR

Breast cancer incidence and poor outcomes are rising in young women, especially among certain racial and ethnic groups, according to a study using TriNetX data.

## Contribution

The study reveals increasing breast cancer incidence and worse outcomes in young women, particularly among non-Hispanic White and Hispanic populations.

## Key findings

- Breast cancer incidence in women aged 18–40 increased from 635 cases in 2014 to 4475 in 2023.
- Mortality and local recurrence rates among young breast cancer patients also increased during the study period.
- Non-Hispanic White women aged 30–39 had the highest incidence, but Hispanic women surpassed them in 2022.

## Abstract

Recent studies suggest a rise in breast cancer (BC) among young women. We analyzed BC incidence patterns among women aged 18–40 in the TriNetX network from 2014 to 2023, stratifying by age, race, and ethnicity. We also examined mortality and local recurrence (LR) in women aged 18–40 diagnosed with primary BC.

This retrospective study used data from the TriNetX network. Female patients aged 18–40 were identified, and the incidence proportion of primary BC from 2014 to 2023 was assessed using the TriNetX Incidence and Prevalence Analytics function, with stratification by age, ethnicity, and race. A second cohort of women aged 18–40 with a primary BC diagnosis was created to evaluate mortality and LR over the same period. All analyses were descriptive.

Among the 18,250,987 women aged 18–40 years in the TriNetX network, the incidence proportion of BC increased from 635 cases in 2014 to 4475 in 2023. White women accounted for the greatest number of BC cases; however, increasing incidence proportions were also observed among American Indian/Alaskan Native (AI/AN), Asian, and Native Hawaiian/Pacific Islanders (NHPIs) women over the last four years. Non‐Hispanic women initially had higher incidence proportions but were surpassed by Hispanic women in 2022. Among 38,683 women aged 18–40 with primary BC, both mortality (0.09%–0.851%) and LR (0.3%–2.9%) increased over the study period.

Within the TriNetX network, BC incidence proportion among women aged 18–40 demonstrated an upward trend from 2014 to 2023, particularly among non‐Hispanic White women 30–39 years old. An uptrend was also seen in young AI/AN, Asian, NHPI, and Hispanic women. In addition, increased documented mortality and LR were also observed. These findings underscore the importance of further research to understand these trends and develop diagnostic and therapeutic approaches tailored to younger patients.