{
  "abstract": "Purpose\n\nThe free triiodothyronine (fT3)/free thyroxine (fT4) ratio is an index estimating the peripheral activity of thyroid hormones. The prognostic role of the fT3/fT4 ratio in colorectal cancer, urothelial cancer, renal carcinoma, and lymphoma is well-recognized, but its effect in metastatic breast cancer remains unestablished.Methods\n\nWe conducted a retrospective study of metastatic breast cancer patients treated with cyclin-dependent kinase (CDK) 4/6 inhibitors at Hacettepe University Hospital. Baseline fT3 and fT4 levels were recorded, and patients were categorized into two groups based on the median fT3/fT4 ratio: Low and High fT3/fT4 Ratio Groups.Results\n\nWe included 162 h-positive/HER2-negative metastatic breast cancer patients. There were no significant differences between the Low and High fT3/fT4 Ratio Groups in terms of age, sex, tumor grade, histopathologic type, menopausal status, sites of metastases, lines of treatment prior to CDK4/6 inhibitors, type of CDK4/6 inhibitor, or endocrine backbone therapy. Of all patients, 47 (29.2%) received two or more lines of treatment before initiating CDK4/6 inhibitors. High fT3/fT4 ratios were associated with significantly longer progression-free survival (PFS) compared to Low fT3/fT4 ratios (median, 9.7 vs. 6.9 months; HR: 0.68; 95% CI: 0.47-0.97; p = 0.035) and significantly longer overall survival (OS) compared to Low fT3/fT4 ratios (median, NR vs. NR months; HR: 0.30; 95% CI: 0.15-0.60; p < 0.001).Conclusions\n\nOur study showed that high fT3/fT4 ratios were independent factors associated with longer PFS and OS in metastatic breast cancer patients treated with CDK4/6 inhibitors, supporting the role of high fT3/fT4 ratios as a prognostic marker.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Medical Oncology, Hacettepe University Cancer Institute, Mehmet Akif Ersoy Sk. 19 A, Altindag, Ankara, 06230, Turkey. drgozdekavgaci@gmail.com.",
    "Department of Medical Oncology, Hacettepe University Cancer Institute, Mehmet Akif Ersoy Sk. 19 A, Altindag, Ankara, 06230, Turkey.",
    "Department of Internal Medicine, Hacettepe University Faculty of Medicine, Ankara, Turkey."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Gozde Kavgaci",
      "orcid": "0000-0001-6960-2024"
    },
    {
      "affs": [
        1
      ],
      "name": "Taha Koray Sahin"
    },
    {
      "affs": [
        2
      ],
      "name": "Naciye Guduk"
    },
    {
      "affs": [
        2
      ],
      "name": "Fırat Sirvan"
    },
    {
      "affs": [
        1
      ],
      "name": "Deniz Can Guven"
    },
    {
      "affs": [
        1
      ],
      "name": "Sercan Aksoy"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/acm28tznb2je7.bib",
  "cited_by": 0,
  "doi": "10.1186/s12885-026-16756-y",
  "fulltext_url": "https://europepmc.org/articles/PMC13753192",
  "id": "acm28tznb2je7",
  "issns": [
    "1471-2407"
  ],
  "landing_url": "https://europepmc.org/article/MED/43009831",
  "language": "eng",
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2730|Advanced Breast Cancer Therapies"
    ]
  ],
  "openalex": "W7203455486",
  "pdf_url": "https://europepmc.org/articles/PMC13753192?pdf=render",
  "pmcid": "PMC13753192",
  "pmid": "43009831",
  "published": "2026-08-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/acm28tznb2je7.ris",
  "sources": [
    {
      "first_seen": "2026-11-12T15:22:43Z",
      "native_id": "MED:43009831",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/43009831"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2730|Advanced Breast Cancer Therapies",
      "subfield": "oncology"
    }
  ],
  "title": "Potential prognostic value of the free T3/T4 ratio in HR+/HER2 - metastatic breast cancer treated with CDK4/6 inhibitors.",
  "title_text": "Potential prognostic value of the free T3/T4 ratio in HR+/HER2 - metastatic breast cancer treated with CDK4/6 inhibitors.",
  "type": "peer-reviewed",
  "updated_at": "2026-11-13T03:20:44Z",
  "url": "https://research.draconitic.com/paper/acm28tznb2je7",
  "venue": "BMC cancer",
  "versions": []
}