Sentinel Lymph Node Biopsy after Neoadjuvant Treatment for Breast Cancer. The Validation Protocol

Introduction: The identification and biopsy of the sentinel lymph node (SLNB) in breast cancer patients requiring neoadjuvant cytostatic treatment (NAC), with clinically negative lymph nodes fhllowing treatment, may be an effective method of de-escalation of axillary surgery. Materials and methods: This prospective study includes 47 cases of breast cancer stage with NAC treatment and complete axillary clinical and imaging response, surgeries perthrmed Prof. :Dr. Alexandru Trestioreanu Oncological Institute in Bucharest (1013) by the same team. In all the cases, SINB was employed using the radioactive tracer method The SI:NB technique with Tc99 radioactive tracer involves: - injection of the radioactive tracer and preoperative lymphoscintigraphy, - intraoperative identification of the sentinel node/ lymph nodes and their excisional biopsy, - intraoperative histopathological examination, in paraffin blocks, and immunohistochernistry of the lymph node (SIN). Results: SLN was identified in 46 of 47 cases. In 19 cases SLN was positive, and in 2 cases we recorded false negative results. All patients underwent standard axillary lymtihadenectomy (back-up lymphadenectomy). The correlation between the intraoperative and paraffin histopathological examination of SIN with the paraffin and immunohistochemical examination of the rest of the axillary nodes (N-SLN) led to the following results: sensitivity 91% (19/ 21), specificity 100% (25/ 25), positive predictive value 100% (19/ 19), negative predictive value 93% (25/ 27). The accuracy or the method was 96% 01/ 16). SIN invasion was more common in patients with residual tumor > 2 cm (vs T <2 cm) (p = 0.01), positive N -SIN (vs non -invaded N-SLN) = 0.003). N-SLNs were more frequently invaded when there was peritumoral lymphocyte invasion (vs. no invasion) (p = 0.01). Cone/usion:SLNI1 in patients with breast cancer who require NAC, with clinically and imaging negative lymph nodes following treatment, has a high rate of specificity and an acceptable number of false negative results. Node invasion is more common in patients with residual tumors > 2 cm, with lymphovascular invasion or with multicenter/ multifocal disease.