Abstract P1-01-29: Intraoperative molecular analysis of sentinel lymph node as a new predictor of axillary status in early breast cancer patients.
Authors: Peg V , Espinosa-Bravo M , Vieites B , Vilardell F , Antúnez JR , de Salas Sancho M , Sansano I , Delgado Sánchez JJ , Pinto W , Gozalbo F , Petit A , Rubio I 
Published: August 2014

The one-step nucleic acid amplification (OSNA) assay (Sysmex Corporation, Kobe, Japan) is a new diagnostic device that uses molecular biological techniques to analyze sentinel lymph node (SLN). Intraoperative SLN assessed by OSNA has been validated as an accurate method for detection of SLN metastasis compared to conventional histological examination. Although recent reports have shown that breast cancer patients with &lt;2 positive SLNs can be spared of a complete axillary lymph node dissection (cALND), there are still a number of patients for whom prediction of non SLN metastasis may be helpful for cALND decision making.

The aim of the present study is to assess the intraoperative positive SLN total tumor load (TTL, defined as the amount of CK19 mRNA copies [copies/μL] in all positive SLNs) obtained by OSNA and to determine whether it is predictive of non-SLNs metastasis independently of the number of affected SLN and the type of surgery.

Data were collected during the month of June 2012 from medical records and include age, tumor size and grade, estrogen and progesterone receptor status, HER2 status, Ki67, presence of lymphovascular invasion (LVI), total number of SLN and non-SLN, number of positive and negative non-SLN, size of SLN and non-SLN metastasis, and TTL in each SLN. A total number of 701 patients were recruited, of which 697 (99,4%) met the study selection criteria. Univariate logistic regression showed that, in addition to TTL (p &lt; 0,001), the number of affected SLNs (p &lt; 0,001), tumor size (p &lt; 0,001), HER2 status (p = 0,007), and LVI (p &lt; 0,001) were predictive of ALND status. The multivariate logistic regression analysis showed that TTL is an independent predictor of metastatic non-SLNs, after adjusting for the tumor size, HER2 status, LVI and, in particular, the number of affected SLNs.

Moreover, the ROC curve analysis showed that, as compared to the number of affected SLN, TTL has a better ROC curve, as measured by the AUC: LogTTL 0.709 (95% CI, 0.667–0.760); number of affected SLN 0.610 (95% CI, 0.570–0.652), p &lt; 0.001. Furthermore, in patients possessing a TTL&lt;15000, the frequency of non-SLN metastasis was 14,7% (NPV = 85,3%, PPV = 41,1%, Sensitivity = 76,7%, Specificity = 55,2%). Taking this value as a cutpoint, 85 patients with mastectomy may have spared a cALND considering the predictive results of the TTL. In seven patients with &gt; 3 positive SLN the TTL was &lt; 15000 so this group, even with 3 positive SLNs, have 14.7% of having additional non SLN metastasis.

In conclusion, TTL by OSNA is a newly standardized, automated, and reproducible tool that predicts axillary node status better and independently of the number of affected SLNs and the type of surgery. This value can then help clinicians to personalize surgical treatment. Prospective studies will be carried out to determine the clinical impact of this variable in the management of patients.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-01-29.