Supervised automated microscopy increases sensitivity and efficiency of detection of sentinel node micrometases in patients with breast cancer

Aims: To investigate the practicality and sensitivity of supervised automated microscopy (AM) for the detection of micrometastasis in sentinel lymph nodes (SLNs) from patients with breast carcinoma. Methods: In total, 440 SLN slides (immunohistochemically stained for cytokeratin) from 86 patients were obtained from two hospitals. Samples were selected on the basis of: (1) a pathology report mentioning micrometastases or isolated tumour cells (ITCs) and (2) reported as negative nodes (NO). Results: From a test set of 29 slides (12 SLN positive patients, including positive and negative nodes), 18 slides were scored positive by supervised AM and 11 were negative. Routine examination revealed 17 positive slides and 12 negative. Subsequently, automated reanalysis of 187 slides (34 patients; institute I) and 216 slides (40 patients; institute II) from reported node negative (NO) patients showed that two and seven slides (from two and five patients, respectively) contained ITCs, respectively, all confirmed by the pathologists, corresponding to 5.9% and 12.5% missed patients. In four of the seven missed cases from institute II, AM also detected clusters of four to 30 cells, but all with a size ≤ 0.2 mm. Conclusions: Supervised AM is a more sensitive method for detecting immunohistochemically stained micrometastasis and ITCs in SLNs than routine pathology. However, the clinical relevance of detecting cytokeratin positive cells in SLNs of patients with breast cancer is still an unresolved issue and is at the moment being validated in larger clinical trials.