RESUMEN
PURPOSE: OSNA is a molecular technique for sentinel lymph node (SN) analysis in breast cancer. Compared to histology, OSNA may yield more (micro)metastases and thereby result in more axillary lymph node dissections or radiotherapy. We investigated whether axillary treatments increase when using OSNA, applying current guidelines for de-escalating axillary management. METHODS: All patients treated for cT1-3N0 breast cancer in our hospital between December 2013 and February 2016 were included. In 148 prospectively included patients (January 2015-February 2016), SN's were examined with OSNA. In a retrospective cohort of 123 patients (December 2013-December 2014), SN's were examined with conventional histology. Outcomes were: number of macro and micrometastases, amount of patients receiving axillary dissection or irradiation, number of patients receiving adjuvant systemic therapy. Data were analyzed using Mann-Whitney and Pearson Chi-square test. P < 0.05 was considered statistically significant. RESULTS: 230 SN's from 123 patients were examined with conventional histology. 229 SN's from 148 patients were evaluated with OSNA. Amount of macrometastases was equal between groups (histology 17.9% versus OSNA 16.2%, p = 0.715). We found significantly more micrometastases when using OSNA (histology 11.4% versus OSNA 25.0%, p = 0.004). Total number of axillary lymph node dissections was comparable in both groups (histology 12.2%, OSNA 12.2%, p = 0.993), as well as number of axillary radiations (histology 8.9%, OSNA 11.5%, p = 0.493). Also, the number of patients receiving adjuvant systemic therapy was similar between conventional histology and OSNA (histology 53.7% versus OSNA 58.1%, p = 0.462). CONCLUSION: OSNA analysis for SN in breast cancer is a highly sensitive technique, detecting more micrometastases than standard histology. When applying current guidelines, OSNA analysis does not lead to overtreatment with more axillary dissections or irradiation.