Breast Cancer Recurrence in Initially Clinically Node-Positive Patients Undergoing Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy in the NEOSENTITURK-Trials MF18-02/18-03.

backgroundThis study aims to identify factors predicting recurrence and unfavorable prognosis in cN+ patients who have undergone sentinel lymph node biopsy (SLNB) following neoadjuvant chemotherapy (NAC).

methodsThe retrospective multi-centre "MF18-02" and the prospective multi-centre cohort registry trial "MF18-03" (NCT04250129) included patients with cT1-4N1-3M0 with SLNB+/- axillary lymph node dissection (ALND) post-NAC.

resultsA total of 2407 cN+ patients, who later achieved cN0 status after NAC and subsequently underwent SLNB, were studied. The majority had cT1-2 (79.1%) and N1 (80.7%). After a median follow-up time of 41 months, the rates of locoregional recurrence and axillary recurrence (AR) were 1.83% and 0.37%, respectively. No significant difference in locoregional recurrence or AR rates was observed between the SLNB/targeted axillary dissection-only (n = 1470) and ALND (n = 937) groups. Factors significantly linked with AR included age younger than 45 years, nonpathological complete response (non-pCR) in the breast, and nonluminal pathology. Locoregional recurrences were associated with nonluminal or HER2(+) pathology, non-pCR in the breast, and ALND. Poor prognostic factors for disease-free survival (DFS) included having cT3-T4, no breast pCR (non-pCR), ypN(+), and nonluminal pathology. No significant difference was found in DFS or disease-specific survival (DSS) rates among ypN0, ypN-isolated tumour cells, ypNmic, and ypN1. However, significant decreases in DFS and DSS rates were observed when comparing ypN2 or ypN3 disease with ypN0.

conclusionsThe present large registry data indicate that younger patients (<45), those with nonluminal pathology, and those who only partially respond in the breast are more susceptible to axillary and locoregional recurrences.