Molecular Proliferation Marker Ki-67 in Breast Cancer: The Role of Vitamin D Status, Hormone Receptor Expression, and Clinicopathological Factors—A Cross-Sectional Study
4 affiliations
- 1Faculty of Health Sciences, WSEI University, 20-209 Lublin, Poland
- 2Faculty of Medical and Health Sciences, University of Siedlce, 08-110 Siedlce, Poland
- 3Department of Health Education, Faculty of Nursing Development, Medical University in Lublin, 20-059 Lublin, Poland
- 4Institute of Psychology and Pedagogy, WSEI University, 20-209 Lublin, Poland
Abstract
Ki-67 is a well-established nuclear biomarker of tumor cell proliferation with key importance for the molecular classification and prognostic stratification of breast cancer. This cross-sectional study included 101 women with histopathologically confirmed invasive breast cancer treated at the St. John of Dukla Oncology Center of the Lublin Region (COZL), Poland (2018–2019). Ki-67 expression was assessed immunohistochemically on formalin-fixed, paraffin-embedded tumor tissue, and independent predictors were identified using multiple linear regression. The median Ki-67 was 20% (IQR: 15–40%). Ki-67 differed significantly between molecular subtypes (Kruskal–Wallis test H = 16.122; p = 0.001; η2 = 0.138): Luminal A tumors had the lowest Ki-67 (median 18%), whereas the Luminal B, HER2-enriched, and Triple-negative subtypes showed higher values (median 30% each). Ki-67 was significantly lower in tumors expressing the estrogen receptor (p = 0.005) and progesterone receptor (p = 0.023). Because the Luminal A/B distinction incorporates a Ki-67 threshold by definition, a multivariable model excluding molecular subtype was fitted using ER, PR, HER2, menopausal status, age, BMI category, and 25(OH)D as candidate predictors. This model identified HER2 positivity (b = 11.26; p = 0.024) and postmenopausal status (b = 17.93; p = 0.017) as independent predictors of higher Ki-67, with a borderline inverse association for age (b = −0.65; p = 0.092); the model explained 10.1% of variance (R2 = 0.101; F(3,95) = 3.574; p = 0.017), and neither ER, PR, BMI, nor 25(OH)D were retained. Serum 25(OH)D concentration showed no meaningful association with Ki-67, either unadjusted (Spearman ρ = 0.035; p = 0.730) or when forced into the retained multivariable model regardless of significance (adjusted b = −0.032; 95% CI: −0.337–0.272; p = 0.834); no association was observed between circulating 25(OH)D and Ki-67 in this cohort, although indirect biological relationships cannot be excluded.
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BibTeX
@article{weber2026molecular,
title = {{Molecular Proliferation Marker Ki-67 in Breast Cancer: The Role of Vitamin D Status, Hormone Receptor Expression, and Clinicopathological Factors—A Cross-Sectional Study}},
author = {Dorota Weber and Robert Łuczyk and Anna Pacian and Teresa Kulik and Monika Baryła-Matejczuk},
journal = {International Journal of Molecular Sciences},
year = {2026},
month = oct,
doi = {10.3390/ijms27198797},
url = {https://www.mdpi.com/1422-0067/27/19/8797},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Molecular Proliferation Marker Ki-67 in Breast Cancer: The Role of Vitamin D Status, Hormone Receptor Expression, and Clinicopathological Factors—A Cross-Sectional Study
AU - Dorota Weber
AU - Robert Łuczyk
AU - Anna Pacian
AU - Teresa Kulik
AU - Monika Baryła-Matejczuk
PY - 2026
DA - 2026/10/01
JO - International Journal of Molecular Sciences
DO - 10.3390/ijms27198797
UR - https://www.mdpi.com/1422-0067/27/19/8797
AB - Ki-67 is a well-established nuclear biomarker of tumor cell proliferation with key importance for the molecular classification and prognostic stratification of breast cancer. This cross-sectional study included 101 women with histopathologically confirmed invasive breast cancer treated at the St. John of Dukla Oncology Center of the Lublin Region (COZL), Poland (2018–2019). Ki-67 expression was assessed immunohistochemically on formalin-fixed, paraffin-embedded tumor tissue, and independent predictors were identified using multiple linear regression. The median Ki-67 was 20% (IQR: 15–40%). Ki-67 differed significantly between molecular subtypes (Kruskal–Wallis test H = 16.122; p = 0.001; η2 = 0.138): Luminal A tumors had the lowest Ki-67 (median 18%), whereas the Luminal B, HER2-enriched, and Triple-negative subtypes showed higher values (median 30% each). Ki-67 was significantly lower in tumors expressing the estrogen receptor (p = 0.005) and progesterone receptor (p = 0.023). Because the Luminal A/B distinction incorporates a Ki-67 threshold by definition, a multivariable model excluding molecular subtype was fitted using ER, PR, HER2, menopausal status, age, BMI category, and 25(OH)D as candidate predictors. This model identified HER2 positivity (b = 11.26; p = 0.024) and postmenopausal status (b = 17.93; p = 0.017) as independent predictors of higher Ki-67, with a borderline inverse association for age (b = −0.65; p = 0.092); the model explained 10.1% of variance (R2 = 0.101; F(3,95) = 3.574; p = 0.017), and neither ER, PR, BMI, nor 25(OH)D were retained. Serum 25(OH)D concentration showed no meaningful association with Ki-67, either unadjusted (Spearman ρ = 0.035; p = 0.730) or when forced into the retained multivariable model regardless of significance (adjusted b = −0.032; 95% CI: −0.337–0.272; p = 0.834); no association was observed between circulating 25(OH)D and Ki-67 in this cohort, although indirect biological relationships cannot be excluded.
SN - 1422-0067
ER -