Predicting Nonsentinel Node Metastases in Sentinel Node-Positive Breast Cancer: What Have We Learned, Can We Do Better, and Do We Need To?

Abstract

Sentinel lymph node (SLN) biopsy has become standard care for lymph node staging in breast cancer, represents a substantial step in the evolution of breast cancer surgery toward greater conservatism, and is one of the great success stories in contemporary surgical oncology. The most salient surgical questions (feasibility, accuracy, case selection, technique, and morbidity) have been asked and answered, and it is increasingly difficult to generate debate on any of them. In contrast, most aspects of SLN pathology remain controversial and elude consensus. Is intraoperative assessment worthwhile? Which method (frozen section, touch prep or smear) is best? How should SLN be processed for permanent pathology [single-section hematoxylin and eosin (H&E) and/or serial sections and/or immunohistochemistry (IHC)]? What is the prognostic significance of SLN micrometastases, especially those detected only by IHC, or as pN0i+ disease (£0.2 mm in size)? Is completion axillary dissection (ALND) required for all patients with SLN who are positive on final pathology? Is there a low-risk group for whom ALND is unnecessary and can we reliably identify this group? All of these issues are highly interrelated, but the last remains the most perplexing for surgeons and is the subject of a substantial literature. What have we learned?