De-Escalation Surgery in cT3-4 Breast Cancer Patients after Neoadjuvant Therapy: Predictors of Breast Conservation and Comparison of Long-Term Oncological Outcomes with Mastectomy.

BACKGROUND: Neoadjuvant therapy (NAT) has become increasingly employed for the treatment of cT3-4 breast cancer (BC), enabling breast-conserving surgery (BCS) in cases traditionally considered for mastectomy. This study aims to identify predictors for breast conservation post-NAT and to evaluate whether BCS influences long-term oncological outcomes. METHODS: We retrospectively analyzed data from patients with cT3-4 BC who received NAT at the Breast Unit of IRCCS Humanitas Research Hospital, Milan, Italy, from October 2009 to April 2020. Surgical outcomes and long-term oncological results, such as disease-free survival (DFS), distant DFS (DDFS), overall survival (OS), and BC-specific survival (BCSS), were compared between the BCS and mastectomy groups. RESULTS: Among 114 patients analyzed, 37 (32.5%) underwent BCS, and 77 (67.5%) had a mastectomy. The key predictors for opting for BCS included absence of vascular invasion, reduced tumor size post-NAT, and achieving ypT0 status. No significant differences in DFS, DDFS, OS, and BCSS were observed between the two surgical groups (log-ranks, p = 0.520, p = 0.789, p = 0.216, p = 0.559, respectively). CONCLUSIONS: BCS after NAT is a feasible and safe option for patients with cT3-4 BC, without adversely affecting long-term oncological outcomes. Identifying predictors of breast conservation can guide surgical decision-making, ensuring that patients receive optimal treatment.

The Impact of Different Patterns of Residual Disease on Long-Term Oncological Outcomes in Breast Cancer Patients Treated with Neo-Adjuvant Chemotherapy.

BACKGROUNDS: The majority of breast cancer (BC) patients treated with neo-adjuvant chemotherapy (NAC) achieves a pathologic partial response with different patterns of residual disease. No clear correlation between these patterns and oncological results was described. Our aims were to define the predictive factors for different patterns of residual disease and compare the outcomes between the scattered versus the circumscribed pattern. METHODS: We reviewed 219 postoperative surgical specimens. Patients were divided into two groups: scattered versus circumscribed. Disease-free survival (DFS), distant DFS (DDFS), and overall survival (OS) were analyzed. RESULTS: The scattered and circumscribed patterns were assessed in 111 (50.7%) and 108 (49.3%) patients. Two independent predictive factors for the circumscribed pattern were identified: discontinuation of NAC cycles (p = 0.011), and tumor size post-NAC >18 mm (p = 0.022). No difference was observed in terms of DFS and DDFS. Patients with the scattered pattern exhibited a statistically significant better OS. Discontinuation of NAC cycles, tumor size >18 mm, triple-negative BC, and ypN+ were associated with increased recurrence and poorer survival. CONCLUSIONS: Discontinuation of NAC cycles and tumor size are independent factors associated with patterns of residual disease. The scattered pattern presents better survival. Understanding the relationship between NAC, the residual pattern, and differences in survival outcomes offers the potential to optimize the therapeutic approaches.