Quantitative Molecular Analysis of Sentinel Lymph Node May Be Predictive of Axillary Node Status in Breast Cancer Classified by Molecular Subtypes

Abstract

To determine the performance of intraoperative one-step nucleic acid amplification (OSNA) assay in detecting sentinel lymph node metastases compared to postoperative histology taking into account breast cancer molecular classification and to evaluate whether the level of cytokeratin 19 mRNA copy number may be useful in predicting the likelihood of a positive axillary lymph node dissection. OSNA assay was performed in a prospective series of 903 consecutive sentinel lymph nodes from 709 breast cancer patients using 2 alternate slices of each sentinel lymph node. The remaining 2 slices were investigated by histology. Cytokeratin 19 mRNA copy number, which distinguishes negative cases (<250 copies), micrometastases (+, ≥250≤5000 copies) and macrometastases (++, >5000 copies), was compared to axillary lymph node dissection status and to the biological tumor profile. Concordance between OSNA and histopathology was 95%, specificity 95% and sensitivity 93%. Multiple Corresponce Analysis and logistic regression evidenced that positive axillary lymph node dissection was significantly associated with a higher cytokeratin 19 mRNA copy number (>5000; p<0.0001), HER2 subtype (p = 0.007) and lymphovascular invasion (p<0.0001). Conversely, breast cancer patients with cytokeratin 19 mRNA copy number <2000 mostly presented a luminal subtype and a negative axillary lymph node dissection. We confirmed that OSNA assay can provide standardized and reproducible results and that it represents a fast and quantitative tool for intraoperative evaluation of sentinel lymph node. Omission of axillary lymph node dissection could be proposed in patients presenting a sentinel lymph node with a cytokeratin 19 mRNA copy number <2000 and a Luminal tumor phenotype.

The Association between Sentinel Lymph Node Metastasis and Ki-67 Labeling Index

“…These findings were in accordance with previous reports [7][8][9][10][11][12][13]. Our study could not find out the association between molecular subtype and SLN metastasis, in contrast with previous reports [3,6,[14][15][16][17][18][19][20][21][22]. Possible explanation to the discrepancy between previous reports and our results is that the distribution in among subtype might affect the results: HER 2 type was very few (7.0%), and this seems to be the reason why low frequency of SLN metastasis in HER 2 subtype was shown in our study.…”

“…A various clinicopathological factors have been identified as independent predictors of axillary lymph node metastasis in early stage breast cancer [6]. These include clinical palpability [7][8][9][10], tumor size [7][8][9][10][11][12][13], lymphatic or vascular involvement [7][8][9][10][11]13], tumor grade [7,10], hormone receptor (HR) status [12,13], age [8,11,12], and molecular subtypes [3,6,[14][15][16][17][18][19][20][21][22].…”

A new clinical cut-off of cytokeratin 19 mRNA copy number in sentinel lymph node better identifies patients eligible for axillary lymph node dissection in breast cancer

“…Among these, the study of Buglioni et al 22 demonstrated that a specific cut-off of 2000 CK19 mRNA copy numbers in the SLN could predict the likelihood of finding positive ALN, identifying patients who are eligible for ALND. This copy number was obtained from the molecular analysis of only a part of the SLN: indeed, this cut-off was based on a 4-slice model and only half of the SLN was used for OSNA.…”

Modelo predictivo multiparamétrico del estatus axilar en pacientes con cáncer de mama: carga tumoral total y perfil molecular. Estudio multicéntrico

“…A pesar de estar bien establecidas las diferencias pronósticas entre los distintos PM, son muy escasos los estudios que lo aplican en la evaluación de riesgo de axila metastásica 21,35 . Buglioni et al demuestran, incluyendo el PM en el estudio multivariante, que los subtipos agresivos como el HER2, se asocian a mayor porcentaje de metástasis axilares 20 .…”

“…Por otra parte, se ha descrito que la tasa de metástasis axilares no centinelas varía en relación al inmunofenotipo tumoral (PM) 19,20 .…”