Abstract PS2-01-28: Factors influencing surgical decision-making in breast cancer using patient-reported outcomes- A multicenter collaborative study-

Abstract Background: Surgical decision-making in breast cancer involves not only clinical and oncological considerations but also psychosocial factors such as personal values, social support, and anticipated quality of life. Although shared decision-making (SDM) is increasingly emphasized, factors influencing patients’ surgical choices remain unclear. This study aimed to identify determinants associated with the selection of total mastectomy (MT), breast-conserving surgery (BCS), or immediate breast reconstruction (IBR) using patient-reported outcomes. Patients and Methods: A multicenter study was conducted across six institutions in Japan. We included 577 female patients who underwent breast cancer surgery between 2008 and 2018. Using patient-reported outcomes, we collected data on sociodemographic background and 15 decision-influencing factors, including opinions of healthcare providers, family, and peers; radiation therapy; fear of recurrence; hospitalization; and perceived impacts on childcare, work, and hobbies. Patients were categorized into MT, BCS, or IBR groups. Chi-square tests were used for group comparisons, and multinomial logistic regression was performed using the IBR group as the reference. Results: Among 577 patients, 194 underwent MT, 185 BCS, and 198 IBR. The mean age was 53.6 years (±11.5), with the IBR group significantly younger (48.2) than MT (58.1) and BCS (54.8) (p<0.001). The mean interval from surgery to questionnaire response was 56.0 months. IBR patients were more likely to have avoided chemotherapy (p<0.001), be non-smokers (p<0.001), have smaller tumors (p<0.001), no nodal metastasis (p=0.003), and be full-time employed (p<0.001). The incidence of postoperative complications (grade ≥3) was highest in the IBR group (p<0.001). The most reported influence was the surgeon’s opinion (92.2%), followed by fear of recurrence (43.8%), partner’s opinion (35.5%), family (22.4%), and breast cancer survivors (21.0%). Patients influenced by nurses were more likely to select IBR (MT: 3.1%, BCS: 4.5%, IBR: 10.8%; p=0.004). Other significant differences included partner’s opinion (p=0.012), hospitalization (p=0.022), radiation therapy (p<0.001), recurrence fear (p=0.002), and concerns about hobbies (p=0.004) and work (p=0.025). Univariable analysis showed that IBR was more likely in patients who were younger (p<0.001), had smaller tumors (p<0.001), no nodal metastasis (p=0.036), no chemotherapy (p=0.007), were non-smokers (p=0.001), employed full-time (p<0.001), and had higher income (p=0.004). IBR was also associated with influence from nurses (p=0.005), partners (p=0.005), hospitalization (p=0.009), hobbies (p=0.017), and work concerns (p=0.011). Recurrence fear was associated with higher IBR selection over BCS (p=0.017). In multivariable analysis, independent predictors of selecting IBR over both MT and BCS included younger age (p<0.001), non-smoking status (p=0.012), being influenced by nurses’ opinions (p=0.022), and absence of fear of cancer recurrence (p=0.042). Conclusions: This study is the first large-scale, multicenter collaborative study to identify factors influencing surgical decision-making in Japanese breast cancer patients. Predictors influencing the choice of IBR compared with MT and BCS were age, smoking status, nurses' opinions, and anxiety about recurrence. The results of this study suggest the importance of multidisciplinary collaboration and surgical decision-making support that considers the individual background of patients. Citation Format: H. Seki, T. Komiya, M. Kato, Y. Sowa, J. Takano, Y. Nishida, N. Tamura, M. Saiga. Factors influencing surgical decision-making in breast cancer using patient-reported outcomes- A multicenter collaborative 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 PS2-01-28.