{
  "abstract": "Background and Objectives: Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) are standard first-line treatment for hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer, yet the cost architecture across the full treatment trajectory remains poorly characterized. This study aimed to characterize phase-specific healthcare costs using a Japanese nationwide claims database.\n\nMethods: We conducted a retrospective cohort study using the DeSC-IQVIA integrated Claims data (April 2014–May 2025). Patients with HR+/HER2- metastatic breast cancer who initiated first-line CDK4/6i were identified. Healthcare costs were decomposed into drug, non-drug inpatient, and non-drug outpatient components across eight treatment phases. Death-anchored analysis evaluated cost structure over the final 12 months of life among decedents.\n\nResults: Among 5435 patients (median age 72.3 years), active treatment phases showed drug-dominated cost structures: first-line per-patient per-month (PPPM) cost was 482,936 Japanese yen (JPY) (drug 85%–90%), second-line 361,615 JPY (81%), and extended chemotherapy 255,922 JPY (66%). A marked inversion occurred in the palliative phase (PPPM 233,824 JPY; drug 11%, inpatient 70%) and terminal phase (PPPM 412,149 JPY; drug 17%, inpatient 69%). Death-anchored analysis of 1111 decedents identified a transition 2 months before death, when inpatient costs first exceeded drug costs. Individual fixed-effects models estimated the CDK4/6i-associated cost increment at 239,815 JPY/month (p < 0.001), corresponding to a total treatment-associated cost of 2.99 million JPY per patient.\n\nConclusions: The cost architecture of CDK4/6i-treated metastatic breast cancer follows a predictable trajectory from drug-dominated active treatment to hospitalization-dominated end-of-life care, with a structural transition approximately 2 months before death. These findings support phase-specific healthcare resource allocation and economic modeling.\n\nSupplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s40261-026-01591-7.",
  "abstract_shown": true,
  "affiliations": [
    "Comprehensive Unit for Health Economic Evidence Review and Decision Support (CHEERS), Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 Japan",
    "Division of Health Policy and Management, Department of Biomedical Science, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 Japan"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Munenobu Kashiwa",
      "orcid": "0000-0001-5178-611X"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Kensuke Moriwaki"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2sdx6cnqvgjh2.bib",
  "cited_by": 0,
  "doi": "10.1007/s40261-026-01591-7",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13723614/",
  "id": "2sdx6cnqvgjh2",
  "issns": [
    "1173-2563",
    "1179-1918"
  ],
  "landing_url": "https://doi.org/10.1007/s40261-026-01591-7",
  "language": "en",
  "licence": "CC-BY-NC-4.0",
  "licence_label": "CC BY-NC 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Original Research Article"
    ],
    [
      "openalex",
      "2002|Economic and Financial Impacts of Cancer"
    ]
  ],
  "openalex": "W7214682310",
  "pdf_url": "https://link.springer.com/content/pdf/10.1007/s40261-026-01591-7.pdf",
  "pmcid": "PMC13723614",
  "pmid": "42806185",
  "published": "2026-09-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2sdx6cnqvgjh2.ris",
  "sources": [
    {
      "first_seen": "2026-11-04T12:22:13Z",
      "native_id": "PMC13723614",
      "source": "pmc",
      "url": "https://doi.org/10.1007/s40261-026-01591-7"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "journal-openalex:F27",
      "subfield": "general"
    }
  ],
  "title": "Healthcare Cost Patterns in CDK4/6 Inhibitor-Treated HR+/HER2- Metastatic Breast Cancer",
  "title_text": "Healthcare Cost Patterns in CDK4/6 Inhibitor-Treated HR+/HER2- Metastatic Breast Cancer",
  "type": "peer-reviewed",
  "updated_at": "2026-11-05T12:20:24Z",
  "url": "https://research.draconitic.com/paper/2sdx6cnqvgjh2",
  "venue": "Clinical Drug Investigation",
  "versions": []
}