Breast cancer detection in axillary sentinel lymph nodes: the impact of the method of pathologic examination

At Carolinas Medical Center, before 2008, axillary sentinel lymph nodes (SLNs) from breast cancer patients were evaluated with a single hematoxylin and eosin-stained slide. In 2008, the protocol changed to include a limited step sectioning at 500 μm. In this study, we compared the intraoperative and permanent section pathologic findings for SLN biopsies from 2006 to 2007 to those from 2009 to 2010. We hypothesized that evaluating 2 slides would increase the detection of micrometastases and isolated tumor cells (ITCs) on permanent sections and correspondingly decrease the sensitivity of intraoperative touch preparation cytology (IOTPC). From 2006 to 2007, 140 (23.5%) of 597 of SLN permanent sections contained tumor cells: 92 macrometastases (65.7%), 36 micrometastases (25.7%), and 12 ITCs 0.2 mm or less (8.6%). The sensitivity of IOTPC for 2006 to 2007 was 51.4% for any tumor cells and 71.7% for macrometastases. From 2009 to 2010, 160 (21.9%) of 730 SLN permanent sections were positive for any tumor cells: 76 macrometastases (47.5%), 55 micrometastases (34.4%), and 29 ITCs (18.1%). The sensitivity of IOTPC for 2009 to 2010 was 39.4% for any tumor cells and 76.3% for macrometastases. With limited step sectioning, we observed an approximately 10% increase in the detection of both micrometastases and ITCs in SLN. The increased detection of ITCs on permanent sections reached statistical significance (P = .018). However, under current clinical guidelines, patients with limited SLN involvement may not be required to undergo completion axillary lymph node dissection. The ability to detect SLN tumor deposits less than 2 mm must be balanced with the clinical utility of doing so.