Factors associated with axillary conversion after neoadjuvant chemotherapy in initially node positive breast cancer patients: A transSENTINA analysis.

Abstract

567 Background: Current study concepts in early breast cancer after neoadjuvant chemotherapy (NAT) are aiming at reducing morbidity by omission of axillary surgery in selected patients. Selection criteria for this strategy have to include the probability of conversion from cN1 to ycN0. We analyzed the association of clinical/pathological parameters and axillary conversion with data from arms C and D of the SENTINA trial (Kühn T et al., Lancet Oncol 2013). Methods: Patients were recruited to Arms C/D of the SENTINA trial in case they presented with clinically positive nodes before NAT. Based on their response to NAT they were then assigned to either arm C (clinically conversion to ycN0) or arm D (no clinical conversion (ycN+). In both the pre- and post-NAT scenarios, clinically involved lymph nodes were defined as palpable and/or suspect by ultrasound. Univariate logistic regression analyses were carried out to evaluate the association between clinical/pathological parameters and axillary conversion after NAT. Results: Of the 892 patients in arms C and D of the SENTINA trial 716 were evaluable for this analysis. After NAT, 593 patients converted to ycN0 and were therefore assigned to arm C; in contrast, 123 patients still had involved lymph nodes after NAT (ycN+) and were assigned to Arm D. Arms C and D were compared regarding the clinical/pathological parameters tumor diameter by ultrasound before and after NAT, grading, multifocality, ER status, PR status, HER2 status, pathological complete remission in the breast (breast pCR), morphology, lymphovascular invasion (LVI) and hemangiosis. Only small tumor diameter after NAT (p = 0.0038), achievement of breast pCR (p = 0.0001) and lack of LVI (p = 0.0009) were positively associated with axillary conversion from cN1 to ycN0 after NAT. Conclusions: Because of the small patient number in arm D, we were not able to identify an association between parameters of tumor biology (ER, PR, HER2 and TN status) and axillary conversion. However, favorable response of the primary tumor (represented both clinically by tumor diameter after NAT and pathologically by pCR in the breast) were positively associated with conversion from cN1 to ycN0. These results justify including patients with clinical and pathological response of the primary tumor in trials investigating de-escalation of axillary surgery after NAT.