Clinical Significance of Micrometastases and Isolated Tumor Cells in Breast Cancer

We decided to do a literature search for information about the clinical significance of micrometastases (pN1mi) and isolated tumor cells (ITCs). A detailed search was conducted in the existing bibliography. We found that pN1mi and ITCs had differences in prognosis and were handled in a different way. However, some researchers do not accept this difference. Many studies have shown no differences in their prognosis and the distinction of these terms is questioned. This fact is attributed to different definitions, diagnostic approaches that have been used and not well organised research. For their diagnosis, single hematoxylin and eosin (H) stain slide section, and not routine immunohistochemical (IHC) stain, is recommended, despite a lot of institutions perform multiple level sections and IHC stains for each block of sentinel lymph nodes (SLNs). Once the limits within pN1mi and ITCs were defined, they have been based in small data, and here is an area where we should focus and build evidence based definitions that have proven differences and importance in clinical management. As for their therapy, in ITCs cases, axillary lymph node dissection (ALND) is omitted, but a large amount of data questions the safety of this omission. In pN1mi cases, ALND is performed.