Diagnosis of the sentinel lymph node in breast cancer: a reproducible molecular method: a multicentric Spanish study.

Aims: Standardization of the sentinel node (SN) as a diagnostic tool has not yet been achieved, because the protocol for histopathological study is highly variable between centres. We compared the results of a new method with conventional histological tests and evaluated its feasibility for intra-operative evaluation, and propose it as a method to standardize the sentinel node evaluation procedure.

Methods And Results: Trial 1 included 181 cases; in parallel, 2-mm-thick sections of the SN were processed alternately for histological analysis and for the one-step nucleic acid amplification (OSNA) procedure. A final concordance of 99.45% was observed in the first trial of our study. For trial 2, the timing of every procedural step was recorded in an electronic database in order to discern the time spent for each step, the total SN evaluation time and to identify areas of improvement. In the second trial, after a learning period and feedback on data recorded, we spent a mean of 31 min for the entire SN evaluation procedure.

Conclusion: Our multi-centric trial using the OSNA assay for sentinel node evaluation in breast cancer demonstrates that this is a highly sensitive, specific and reproducible technique that allows for standardization of the SN diagnostic procedure, a necessary, and until now unresolved, issue.