Early deviations from guideline-concordant care in triple-negative breast cancer: A patient-reported analysis.

e13528 Background: Timely, guideline-concordant care (GCC) is critical to optimize outcomes in triple-negative breast cancer (TNBC). However, deviations from established guidelines often occur early in the care continuum, including symptom misinterpretation by patients or providers, delayed or incomplete diagnostic evaluation, and fragmented transitions to treatment. While quantitative studies have documented variability in treatment timeliness, patient-reported factors driving deviations from GCC during the early care pathway are poorly understood. Methods: As part of a larger mixed-methods study, we conducted a qualitative analysis using semi-structured interviews with a purposive sample of women with TNBC receiving treatment between 2017 and 2022 (n = 42). We oversampled Black and Hispanic/Latina women for representation. Interviews explored diagnostic experiences, care coordination, communication, treatment preparation, and navigation to treatment initiation. Interviews were recorded, transcribed, and analyzed using thematic analysis, iterative coding, and consensus procedures (IRR > 90%), followed by reflexive thematic analysis to refine patterns related to early deviations from guideline-concordant care. The study received independent IRB approval. Results: Participants described multiple, interrelated disruptions in the early care pathway. Diagnostic uncertainty and symptom dismissal, particularly among younger and postpartum women, contributed to delayed diagnostic escalation. Communication gaps and information overload limited understanding of TNBC and readiness for decision-making. Navigation and coordination barriers, including insurance authorization, scheduling delays, and fragmented referrals, impeded timely treatment initiation. Psychosocial shock further compromised patients’ ability to self-advocate during early treatment planning. These factors frequently co-occurred and were compounded during the earliest phases of care. Conclusions: Patient-reported experiences reveal early, potentially modifiable factors contributing to deviations from GCC in TNBC. Although timely diagnosis and treatment initiation are essential in this rapidly progressive disease, the quality of early care also hinges on effective communication, coordinated care transitions, anticipatory symptom guidance, and robust navigation support. When these early-care functions are variable or inadequate (e.g., fragmented transitions, poor referral tracking, or limited decision support), patients are less prepared to make decisions and progress promptly from diagnosis to treatment initiation. These findings highlight a critical opportunity for early, structured interventions at diagnosis to strengthen care coordination, support decision readiness, and reduce preventable disruption in the early TNBC care pathway.