Aim: One-Step Nucleic Acid Amplification (OSNA) can detect isolated tumour loads in axillary lymph nodes of breast cancer patients. We investigated the predictability of the non-sentinel lymph node (SLN) metastatic involvement (MI) based on the OSNA SLN assessment in surgical invasive breast cancer.
Methods: We studied surgical breast invasive carcinoma patients, not taking neoadjuvant chemotherapy, having SLN positive by OSNA and having received axillary lymphadenectomy. Age, basic histopathological, immunohistochemical, SLN biopsy and lymphadenectomy data were compared between patients with or without MI of more than 2 non-SLN in both univariate and multivariate analyses. The discriminating capacity of the multivariate model was characterized by the ROC AUC.
Results: 726 patients from 23 centers in Spain aged 55.3 ± 12.2 years were analysed. The univariate analysis comparing patients with or without MI of more than 2 non-SLN detected statistically significant differences in primary tumour size, multifocality, presence of lymphovascular infiltration, positive proliferation index with ki67, immunophenotype and logTTL (Tumour Total Load). The multivariate logistic analyses (OR (95% CI)) confirmed multifocality (2.16 (1.13-4.13), p = 0.019), lymphovascular infiltration (4.36 (2.43-7.82), p < 0.001) and logTTL (1.22 (1.10-1.35), p < 0.001) as independent predictors, and exhibit an AUC (95% CI) of 0.78 (0.72-0.83) with an overall fit (Hosmer-Lemeshow test) of 0.359. A change in the slope of both sensitivity and specificity is observed at about 10,000 copies/μL, without relevant changes in the Negative Predictive Values.
Conclusions: Using OSNA technique, the MI of more than 2 non-SLN can be reliably predicted.
Keywords: Breast neoplasms; Intraoperative procedures; Keratin 19; One-step nucleic acid amplification assay; Sentinel lymph-node biopsy; mRNA copy number.
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