Abstract P1-01-06: Elaboration of a nomogram to predict the non sentinel node status (NSN) in breast cancer (BC) patients with positive SN, intra-operatively assessed with OSNA (one step nucleic acid amplification) method

Abstract

Abstract BACKGROUND Diagnostic axillary lymph node dissection (ALND) has been replaced by sentinel node biopsy (SNB) in nodal staging. Tumor-positive SNB results in a risk of NSN metastases in case of micro and macro metastases ranging from 10 to 50% respectively. Therefore most of the patients are submitted to an unnecessary ALND. Therefore the development of a mathematical model for predicting patient-specific risk of non sentinel node metastases is strongly warranted. We have developed an European Database with positive SN detected by OSNA molecular method, able to identify intra-operatively patients with micro (CK19 mRNA copies 250-5000) or macrometastases (number of copies > 5000). MATERIAL AND METHODS European OSNA database has been developed, only patients whose SN was totally assessed with OSNA were included. The following parameters were recorded: - Clinical: hospital, age, record number - Bio-patological: tumor size, grading, multifocality, histological type, LVI, ER-PR status, HER-2, KI67, molecular classification (luminal A, luminal B, HER2 like, triple negative) - Sentinel and non-sentinel lymph node related: number of removed SNs, number of positive and negative SNs, copy number of positive sentinel node, ratio: number of positive SN to number of removed SN number of removed and number of positive nodes after ALND. A total of 2351 patients have been included in the database (938 micrometastases and 1413 macrometastases) with the collaboration of 20 European and Italian OSNA centers. Univariate analysis was performed to determine factors associated with NSN metastases. Chi-square test was used for categorigal variables. All variables with p values less than 0.05 were included in the logistic analysis using backward stepwise method. RESULTS Univariate and multivariate analysis for micro and macro metastases are reported. In patients with SN micrometastases, multivariate analysis showed that grading (p<0.006), Tsize (p<0.04) and the number of CK19 mRNA copies (p<0.0001) are strictly related with positivity of NSN status. In patients with macrometastases multivariate analysis selected KI 67 (p<0.04), Tsize (p<0.002), number ofcopies (p<0.0001) and multifocality (p<0.007) as parameters significantly correlated with NSN positivity. CONCLUSIONS In our analysis we have evaluated only parameters available at the time of operation because the final nomogram has to be employed by the surgeons as a guide for the surgical decision-making whether to perform or not ALND in BC women. The large population employed and the power of number of copies are the right prerequisites for a reliable nomogram that will be presented at the Meeting. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-06.