Integrating Biological, Clinical, and Behavioral Factors to Improve Breast Cancer Outcomes - Carolina Breast Cancer Study

Phase 4 of the Carolina Breast Cancer Study (CBCS4) builds on prior phases that examined molecular and epidemiologic differences in breast cancer types and outcomes. Previous findings showed that certain breast cancer subtypes and genetic factors are linked to higher risks. While prior research uncovered subtype-specific risks and relevant genetic loci, persistent disparities especially among African American (AA) and American Indian/Alaska Native (AIAN) women suggest that tumor biology alone does not fully explain outcome differences. Other important factors, like access to healthcare, treatment adherence, patient engagement must also be evaluated. In addition to collecting biological and clinical data, participants will receive a structured behavioral intervention designed to improve communication with providers and self-advocacy during cancer care. This phase includes a structured behavioral intervention designed to improve health communication and self-advocacy, both of which are hypothesized to improve health outcomes. All participants are prospectively assigned to this single-arm intervention, which includes educational resources, symptom reporting tools, reflective self-assessments, and regular engagement with trained study staff over a defined timeline. This study assesses whether structured research participation can positively influence patient behavior and ultimately reduce disparities in breast cancer care. This study also aims to better understand etiology and prognosis of breast cancer, including subtypes such as Luminal A and B, Basal-like, and Human Epidermal Growth Factor Receptor 2 positive (HER2+) / estrogen receptor negative (ER-) and to address disparities driven by both biology and systemic barriers.

Study Population will be 3300 participants with invasive breast cancer among women aged 20-74 in 59 North Carolina counties between will be enrolled. Approximately 1,500 Black women (750 aged \<50 and 750 aged ≥50) and 1,750 non-Black women, including approximately 200 who self-identify as American Indian/Alaska Native (875 \<50, 875 ≥50) will be included. Participants will complete a structured, in-person baseline interview covering breast cancer risk factors, quality of life, comorbidities, initial treatment, follow-up surveys will assess changes in self advocacy. Blood and/or saliva samples will be collected. Participants will provide consent for medical record abstraction and retrieval of tumor blocks.