A standardized sentinel lymph node enhanced pathology protocol (SEPP) in patients with breast cancer

Background and Objectives: Sentinel lymph node (SLN) biopsy allows enhanced pathology with serial sections and immunohistochemical analysis of the retrieved node. We present our experience with a simple, practical, pathology protocol. Methods: We analysed 416 consecutive breast cancer patient who underwent SLN biopsy. These were studied with six couples of sections at three different levels, each stained with hematoxylin-eosin (H/E) and immunohistochemistry (IHC) (MNF 116). Results: With conventional analysis the SLN was positive in 106/416 cases (25%). The addition of serial sections, according to the protocol, allowed diagnoses of micrometastases (MICRO) (n = 22) or isolated tumor cells (ITC) (n = 38) or MICRO (n = 1) in 51/416 patients (14.6%). Specifically, the diagnosis was undertaken at level I (8.9%), level II (4%), or level III (1,6%). The incidence of MICRO or ITC was not different in T1 and T2 cases (13% vs. 15%, P = 0.7). The addition of the third level of analysis added very little both in T1 and T2 cancers (1.3% vs. 3.8%, P = 0.1). Conclusions: Serial sectioning of the SLN allows diagnosis of MICRO and ITC in a significant percentage of cases. Adoption of our protocol seems practical, as the incidence of level III positivity is extremely low, particularly in T1 cancers, and additional sections would be, therefore, unlikely useful.