The predictive value of sentinel node biopsy in early breast cancer after neo-adjuvant chemotherapy: A prospective study

Abstract

ObjectiveA sentinel Node (SN) has replaced axillary lymph node dissection (ALND) in patients with clinically node negative axilla (cN0). SN after Neo-adjuvant chemotherapy (NACT) is feasible but not accurate in clinically node positive (cN1-3) patients. The goal of this study is to determine the negative predictive value (NPV) of SN in cN0 breast cancer after NACT. A secondary endpoint is to determine if ALND can be avoided after NACT regardless of the pre-treatment clinical staging of the axilla, in case of a normalization of the 18F-fluoro-2-deoxy-glucose positron emission tomography scan (PET-CT scan). DesignA single institution prospective study regarding the negative predictive value of the SN in breast cancer after NACT was conducted in the Multidisciplinary Breast Clinic of the Antwerp University Hospital from 29/03/2010 until 01/12/2015 (Study number: B30020108368). Inclusion criteria for study participation were: breast cancer, age above 18 years, female, tumor stages T2-T4 N0-3 or T1N1-N3. All patients were staged by a mammography, ultrasound of the axilla, MRI of the breast, PET-CT scan and bone scintigraphy. They received NACT consisting of 12 cycles of paclitaxel or 4 cycles of docetaxel followed by dose dense doxorubicin or epirubicin/cyclofosfamide or vice versa as a standard initial treatment. After 6 weeks, a PET-CT scan was performed for early tumour response evaluation. At the day of operation, a 99mTC-labelled nanocolloid was used to identify the SN. During the surgery the SN were removed separately together with a complete ALND. ResultsA total of 150 patients were enrolled in our study of which 129 were eligible for analysis. 53 patients had a positive SN of which 32 have a positive axillary lymph nodes (ALN), positive predictive value (PPV) was 60%; 76 patients had a negative SN of which 6 had a positive ALN (NPV 92%). The sensitivity is 84% and the specificity 76% with a false omission rate (FOR) of 8%. In total 45 patients ALN were clinical negative and no suspect lymph nodes were seen on ultrasound, MRI and PET-CT scan) and 45 patients had negative a SN, with no ALN and 2 patients had a positive SN of which 1 patients had axillary involvement (NPV 100%). The FOR of cN1: 5%, cN2: 37%, cN3 33%. A total of 22 patients out of 84 patients (26%) of which 15/49 cN1 (30%), 6/23 (26%) cN2, 1/12 (8%) have after 6 weeks of chemotherapy and normalization on PET-CT scan. A total of 17 patients had a negative SN and ALN. The FOR was in this group was 0%. ConclusionA SNB should become the standard after NACT if case of a cN0. If after NACT the PET CT has normalized, no ALND should be performed if the SN is negative.