Abstract Background: The use of neoadjuvant therapy (NAT) for early-stage breast cancer has increased significantly in recent years. Emerging evidence suggests a link between psychological factors, such as anxiety and depression, and tumor behavior, potentially mediated by the immune microenvironment. While previous studies have demonstrated an association between emotional distress and treatment response in patients with metastatic cancer, data in the early breast cancer setting remain limited. We are conducting a prospective study to examine the relationships between psychosocial factors, immunological biomarkers, and response to NAT in patients with early breast cancer. Here, we present our preliminary findings on the psychosocial characteristics of this patient population. Methods: Patients with early-stage breast cancer who were referred for neoadjuvant chemotherapy with or without biological therapy at a single large academic institution were eligible for the study. Eligible NAT regimens included ddACT, TCHP, ddACTHP, and the KEYNOTE-522 protocol (TCAC + pembrolizumab). After signing informed consent, and prior to administration of the first treatment, blood samples were collected for immuno-proteomic analysis. On the same day, patients completed psychological questionnaires assessing anxiety (GAD-7), self-efficacy in coping with cancer (Cancer Behavior Inventory), social support (MSPSS), and socio-demographic characteristics. Clinical characteristics of the patients and their tumors were extracted from the electronic medical records. Results: At data cutoff, 40 patients had enrolled and completed pre-treatment questionnaires. Among these patients, 6 (15%), 9 (22.5%), 9 (22.5%), and 16 (40%) had estrogen receptor-positive/HER2-negative (ER+/HER2−), ER+/HER2+, ER−/HER2+, and triple-negative breast cancer, respectively. Median age was 46 (range: 25-77). Prior to treatment initiation, 11 patients (27.5%) reported moderate to high anxiety levels, while 29 (72.5%) reported low or no anxiety. No significant correlations were found between breast cancer subtype, tumor size, or nodal involvement and levels of anxiety, self-efficacy, or perceived social support. Women in a relationship reported significantly lower anxiety levels, higher self-efficacy and greater perceived social support compared to single women (p = .033, p = 0.018 and p = 0.017, respectively). Women with lower income levels or those who were unemployed reported significantly lower self-efficacy (p = .022 and p = .007, respectively). Among the 29 patients who completed neoadjuvant treatment and underwent surgery, no significant correlations were found between psychosocial factors and pathological complete response (pCR). However, both chemotherapy dose reduction (DR) and lower relative dose intensity (RDI), each significantly associated with lower pCR rates (p = .044 and p = .039, respectively), were also significantly correlated with lower perceived social support (p = .040 for DR and p = .021 for RDI) and lower self-efficacy (p = .025 for RDI). As expected, pCR rates were significantly associated with breast cancer subtype (p = .019). Conclusions: Moderate to high anxiety was reported by approximately one-quarter of patients with early breast cancer prior to starting NAT. Being in a relationship was associated with lower anxiety, higher self-efficacy, and greater perceived social support. Lower self-efficacy and perceived social support were significantly associated with reduced chemotherapy RDI, which in turn was associated to lower pCR rates. The study is ongoing, and additional data are needed to further explore the associations between psychosocial factors, immunological biomarkers, and response to NAT. Citation Format: Y. Bar, N. Keren, D. Eisenstadt, Y. Hamama-Raz, S. Lerner, I. Zada, I. Shiran, Y. Leshem, S. Strulov Shachar, A. Sonnenblick. Psychosocial determinants in patients with early breast cancer undergoing neoadjuvant therapy: initial results from a prospective study abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-11-13.
Bar et al. (Tue,) studied this question.