Prognostic Value of Metabolic–Muscle Reserve Index in HR+/HER2− Metastatic Breast Cancer Treated with CDK4/6 Inhibitors
- 1Department of Medical Oncology, Manisa Celal Bayar University Faculty of Medicine, Manisa 45030, Turkey
- 2Department of Nuclear Medicine, Manisa Celal Bayar University Faculty of Medicine, Manisa 45030, Turkey
Abstract
Background/Objectives: Despite the established benefits of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, survival outcomes remain heterogeneous among patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer. We developed the Metabolic–Muscle Reserve Index (MMRI), integrating tumor metabolic activity, biochemical status, and skeletal muscle quantity, and investigated its relationship with progression-free survival (PFS) and overall survival (OS). Methods: We conducted a retrospective study involving 168 patients with HR+/HER2− metastatic breast cancer who were treated with CDK4/6 inhibitors. MMRI incorporated baseline PET/CT-derived maximum standardized uptake value (SUVmax), serum lactate dehydrogenase (LDH), albumin, and CT-derived psoas volume index (PVI). Receiver operating characteristic (ROC) analysis identified an exploratory MMRI cut-off. We examined survival using Kaplan–Meier analysis and Cox regression. Results: ROC analysis identified an MMRI cut-off of 10.68 for mortality discrimination, with an AUC of 0.642 (95% CI: 0.563–0.716). Patients with MMRI > 10.68 had shorter median PFS (14.1 vs. 28.1 months; p < 0.001) and OS (29.7 months vs. not reached; p < 0.001) than those with MMRI ≤ 10.68. In multivariable Cox analysis, higher MMRI was associated with shorter PFS (HR: 1.857, 95% CI: 1.329–2.596; p = 0.0003) and OS (HR: 1.974, 95% CI: 1.368–2.846; p = 0.0003). Conclusions: Patients with higher MMRI values experienced shorter PFS and OS during CDK4/6 inhibitor treatment for HR+/HER2− metastatic breast cancer. Given its modest discriminative performance, these findings remain exploratory and require prospective external validation before clinical application.
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BibTeX
@article{kolkıran2026prognostic,
title = {{Prognostic Value of Metabolic–Muscle Reserve Index in HR+/HER2− Metastatic Breast Cancer Treated with CDK4/6 Inhibitors}},
author = {Nagihan Kolkıran and Atike Pınar Erdoğan and Mustafa Şahbazlar and Gözde Mütevelizade and Ferhat Ekinci},
journal = {Journal of Clinical Medicine},
year = {2026},
month = nov,
doi = {10.3390/jcm15218641},
url = {https://www.mdpi.com/2077-0383/15/21/8641},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Prognostic Value of Metabolic–Muscle Reserve Index in HR+/HER2− Metastatic Breast Cancer Treated with CDK4/6 Inhibitors
AU - Nagihan Kolkıran
AU - Atike Pınar Erdoğan
AU - Mustafa Şahbazlar
AU - Gözde Mütevelizade
AU - Ferhat Ekinci
PY - 2026
DA - 2026/11/06
JO - Journal of Clinical Medicine
DO - 10.3390/jcm15218641
UR - https://www.mdpi.com/2077-0383/15/21/8641
AB - Background/Objectives: Despite the established benefits of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, survival outcomes remain heterogeneous among patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer. We developed the Metabolic–Muscle Reserve Index (MMRI), integrating tumor metabolic activity, biochemical status, and skeletal muscle quantity, and investigated its relationship with progression-free survival (PFS) and overall survival (OS). Methods: We conducted a retrospective study involving 168 patients with HR+/HER2− metastatic breast cancer who were treated with CDK4/6 inhibitors. MMRI incorporated baseline PET/CT-derived maximum standardized uptake value (SUVmax), serum lactate dehydrogenase (LDH), albumin, and CT-derived psoas volume index (PVI). Receiver operating characteristic (ROC) analysis identified an exploratory MMRI cut-off. We examined survival using Kaplan–Meier analysis and Cox regression. Results: ROC analysis identified an MMRI cut-off of 10.68 for mortality discrimination, with an AUC of 0.642 (95% CI: 0.563–0.716). Patients with MMRI > 10.68 had shorter median PFS (14.1 vs. 28.1 months; p < 0.001) and OS (29.7 months vs. not reached; p < 0.001) than those with MMRI ≤ 10.68. In multivariable Cox analysis, higher MMRI was associated with shorter PFS (HR: 1.857, 95% CI: 1.329–2.596; p = 0.0003) and OS (HR: 1.974, 95% CI: 1.368–2.846; p = 0.0003). Conclusions: Patients with higher MMRI values experienced shorter PFS and OS during CDK4/6 inhibitor treatment for HR+/HER2− metastatic breast cancer. Given its modest discriminative performance, these findings remain exploratory and require prospective external validation before clinical application.
SN - 2077-0383
ER -