Diagnostic delays, treatment timeliness, and patient experiences in triple-negative breast cancer: a mixed-methods study.

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that disproportionately affects younger patients, and Black and Hispanic/Latina patients. Timely diagnosis and treatment initiation are critical for optimal outcomes, yet variation in care delivery and delays in treatment initiation persist. While administrative data have documented differences in treatment timeliness, less is known about how patients experience the early TNBC care pathway and how these experiences relate to observed healthcare utilization patterns. Methods: We conducted a convergent parallel mixed-methods study integrating qualitative interviews with patients diagnosed with TNBC and a retrospective analysis of administrative claims data. Semi-structured interviews were conducted with 42 patients in the United States, intentionally oversampling Black, Hispanic/Latina, and younger patients. Quantitative analyses examined screening, diagnostic utilization, time to treatment initiation, and post-treatment care utilization among 6,345 commercially insured patients and patients with Medicaid managed care (MMC). Qualitative and quantitative findings were analyzed independently and then integrated to identify areas of convergence, divergence, and expansion. Results: Quantitative analyses identified observed differences in adjusted time to neoadjuvant treatment initiation among Black and Hispanic/Latina patients enrolled in MMC, with adjusted mean times increasing from 44.2 days (95% CI: 40.7-48.0) among White patients to 63.2 days (95% CI: 58.1-68.8) among Hispanic/Latina patients and 82.1 days (95% CI: 75.3-89.4) among Black patients. Qualitative findings provided context for these observed patterns, with participants describing symptom dismissal, difficulties translating complex clinical information into meaningful understanding, insurance-related barriers, and logistical challenges that may affect escalation and treatment readiness. Divergences highlighted limitations of claims-based measures, including their inability to capture emotional distress, uncertainty, feeling unseen within care interactions, fragmented care experiences, and inadequate preparation for treatment side effects. Conclusion: By integrating patient experiences with claims-based analyses, this study provides hypothesis-generating insights into early TNBC care pathways and identifies potential inflection points where health system interventions, particularly patient navigation and tailored education, may support more equitable, coordinated, and patient-centered care, across the TNBC care continuum.