# Examination of factors influencing the racial disparity in fibroid incidence

> **NIH NIH R01** · FRED HUTCHINSON CANCER CENTER · 2024 · $820,115

## Abstract

PROJECT SUMMARY
 Uterine fibroids are the most common pelvic tumors in women of reproductive age, coming to clinical
attention in one in four women. Fibroids are 2-3 times as common among Black women compared to White
women. Each year, fibroids result in $2.2 billion in health care costs and account for over 200,000
hysterectomies. Despite significant quality of life and health care costs associated with fibroids, few modifiable,
factors have been identified, and it is unknown why Black women are disproportionately affected. A major barrier
to understanding the relative contributions of established and yet-to-be identified risk factors that may contribute
to the fibroid disparity is that no single study has adequate numbers of both Black and White women to apply
advanced epidemiologic methods (e.g., mediation analyses, population attribute risks) to evaluate these
differences. Further, while an association between perceived interpersonal racism and fibroids has been shown,
no studies have examined the role of structural racism in fibroid incidence. We propose to study women from
two prospective U.S. cohorts — Black women from the Black Women’s Health Study (BWHS) and White women
from the Nurses’ Health Study II (NHSII) — to identify factors that explain the differences in fibroid incidence
between Black and White women. Among 59,000 participants (6,200+ newly diagnosed cases) in the BWHS
and 116,429 (8,100+ newly diagnosed cases) in the NHSII, we will examine the following specific aims:
 Aim 1. Determine if established fibroid risk factors (e.g., parity, age at menarche, smoking, body size),
which differ in prevalence or timing between Black and White women, contribute to racial disparities in the risk
of uterine fibroids. We will calculate race-specific population attributable fractions to identify the proportion of
fibroids cases that are attributable to each risk factor and summarize the impact of differences in the
distribution of fibroids risk factors by race on fibroids incidence using a novel average odds ratio method.
 Aim 2. Determine if environmental and neighborhood-level factors, including structural racism,
contribute to the racial disparities in the risk of uterine fibroids.
 Aim 3. Estimate the contribution of multiple factors simultaneously to the fibroids incidence disparity
between Black and White women using multiple mediation analysis. Factors to be considered for inclusion into
the mediation models include reproductive, lifestyle, psychosocial, and environmental factors, and measures of
structural racism.
 Given that more than 25% of women experience fibroids, the potential health and economic impact of
this novel study is substantial. Black women suffer disproportionately from fibroids, but the reasons for this
disparity are not understood. The identification factors that contribute to the racial disparity in fibroid incidence
could lay the groundwork for identifying strategies that would reduce fibroid incidence, particula...

## Key facts

- **NIH application ID:** 10981951
- **Project number:** 1R01HD113709-01A1
- **Recipient organization:** FRED HUTCHINSON CANCER CENTER
- **Principal Investigator:** Holly Ruth Harris
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $820,115
- **Award type:** 1
- **Project period:** 2024-08-01 → 2029-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10981951

## Citation

> US National Institutes of Health, RePORTER application 10981951, Examination of factors influencing the racial disparity in fibroid incidence (1R01HD113709-01A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10981951. Licensed CC0.

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