Association between obesity and outcomes of first-line CDK4/6 inhibitor therapy in metastatic breast cancer: a multicenter real-world study

Creative Commons License

Gunaltili M., Guliyev M., Birsin Z., Cerme E., Aliyev V., Sen G. A., ...More

SCIENTIFIC REPORTS, vol.16, no.1, 2026 (SCI-Expanded, Scopus)

  • Publication Type: Article / Article
  • Volume: 16 Issue: 1
  • Publication Date: 2026
  • Doi Number: 10.1038/s41598-026-58205-7
  • Journal Name: SCIENTIFIC REPORTS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, EMBASE, MEDLINE, Directory of Open Access Journals, Zoological Record, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Biomedical Reference Collection: Corporate Edition (EBSCO), Health Research Premium Collection (ProQuest)
  • Open Archive Collection: AVESIS Open Access Collection
  • Istanbul University Affiliated: Yes

Abstract

Obesity has been associated with inferior outcomes in early-stage breast cancer, but its clinical relevance in metastatic disease treated with CDK4/6 inhibitors remains uncertain. We retrospectively analyzed 332 patients with hormone receptor-positive/HER2-negative metastatic breast cancer who received first-line ribociclib or palbociclib plus endocrine therapy between 2018 and 2023. Patients were stratified by baseline BMI: <30 kg/m(2 )(n = 221) and >= 30 kg/m(2) (n = 111). Survival outcomes were estimated using Kaplan-Meier and Cox models, and treatment-related adverse events were compared between the groups. The median follow-up duration was 23.1 months. The median PFS was significantly longer in patients with a BMI >= 30 kg/m(2) than in those with a BMI < 30 kg/m(2) (46.5 vs. 23.8 months; p = 0.016). In multivariate analysis, BMI >= 30 kg/m(2) remained significantly associated with longer PFS (HR, 0.679; 95% CI, 0.468-0.985; p = 0.041). The median OS was not reached in either group. Patients with a BMI >= 30 kg/m(2) experienced lower rates of any-grade toxicity and dose-reducing TRAEs. These findings suggest a potential association between BMI and clinical outcomes in this treatment setting. Prospective studies that integrate body composition and pharmacokinetics are required for validation.