Early thelarche, reproductive hormones, and MRI-based breast density: a prospective study in China

Ying Li ¹, Wenqing Liu ¹, Yue Yu ²

⁰Department of Maternal, Child and Adolescent Health, School of Public Health, Ministery of Education Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Hefei, Anhui, China.

Breast Cancer Research : Bcr +

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September 2, 2025

View abstract on PubMed

Summary

Earlier thelarche (breast development onset) in girls is linked to increased breast density, a breast cancer risk factor. Prolonged estrogen exposure may be a key factor for early breast development and density.

Area Of Science

Endocrinology
Oncology
Radiology

Background

Global decline in the age of thelarche (breast development onset) observed.
Earlier menarche linked to higher breast density and breast cancer risk.
Association between early thelarche and breast density remains unclear.

Purpose Of The Study

Investigate the relationship between early thelarche and breast density.
Examine the role of reproductive hormones in this association.
Identify potential targets for breast cancer prevention in girls with early puberty.

Main Methods

114 girls with idiopathic central precocious puberty (ICPP), early thelarche (ET), and normal thelarche (NT) were recruited.
Breast composition measured by MRI 1-year post-menarche.
Reproductive hormone concentrations measured via fasting blood samples at baseline and follow-up.

Main Results

Early thelarche (ET) and ICPP groups showed significantly higher percent fibroglandular volume (%FGV) and fibroglandular volume (FGV) compared to the normal thelarche (NT) group.
Elevated serum estrogen levels observed in the ET group relative to the NT group.
Each year earlier thelarche onset correlated with increased %FGV and FGV; hormonal pathways mediated this association.

Conclusions

Earlier thelarche, even between 8.0-9.0 years, is associated with increased breast density (%FGV and FGV).
Prolonged estrogen exposure is a potential modifiable mediator.
Targeting estrogen exposure may offer breast cancer prevention strategies for girls with earlier puberty.

Keywords:

Breast cancer risk Early thelarche Estradiol Insulin-like growth factor 1 Percent fibroglandular volume Progesterone Puberty timing

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