Analysis of sentinel node biopsy - a single-institution experience supporting the use of serial sectioning and immunohistochemistry for detection of micrometastases by comparing four different histopathological laboratory protocols.

AIMS: Detecting micrometastases (>0.2 and ≤2 mm/>200 cells) and isolated tumour cells (ITCs; ≤0.2 mm/<200 cells) is important for staging of breast cancer patients. The aim of this study was to systematically compare several laboratory protocols used to detect metastases after initial intraoperative frozen section examination.

METHODS AND RESULTS: Four different protocols for the work-up of sentinel lymph nodes (SLNs) after frozen sectioning were applied in the routine diagnostic process from 2001 to 2009. In addition, team-work with a limited number of laboratory technicians and pathologists handling SLNs was introduced in 2008. The present study shows that there were, overall, significantly more node-positive patients in the period when team-work and intensive step sections including immunohistochemistry (IHC) were used (P = 0.01). This resulted in 13% more patients being found to have ITCs and micrometastases than in a time period when only step sections were performed. No increase in the number of false-negative frozen sections was seen.

CONCLUSIONS: Future guidelines for pathological work-up of sentinel nodes in women with breast cancer might include team-work and IHC if frozen sections are used intraoperatively.