Sentinel node concept in breast cancer

It seems that there exists a specific lymph node center called sentinel node (SN) which appears to be the primary site of metastases. The sentinel node concept (SNC) is fundamentally based on the orderly progression of tumor cells within the lymphatic system. It is the most important new concept in surgical and radiation oncology. The purpose is to present the biological significance, the diagnostic and clinical basis of the sentinel node concept in breast cancer patients.

Lymphoscintigraphy and gamma probe biopsy is necessary to show predictable lymph flow to the regional sentinel node, to multiple sentinel nodes or unpredictable lymph flow to extra-regional sentinel nodes and for performing sentinel node procedure. The standard protocol for the evaluation of the sentinel node metastases consists of extensive histopathological investigation including step Hematoxylin & Eosin (H&E) stained sections and immunohistochemistry.

A high rate of success of the identification of the sentinel node for breast cancer was reported. The presence or absence of metastasis in this node is a very accurate predictor of overall nodal status. The temptation to examine the sentinel node with the greatest possible degree of accuracy highlights one of the major problems related to sentinel node biopsy. The success of the sentinel node procedure depends primarily on the adequate functional capacity necessary for sufficient uptake to ensure the accurate identification. In negative sentinel-node patients a complete axillary lymph node dissection is avoidable. In sentinel-node positive patients and clinically negative patients a postoperative radiotherapy would permit an adequate tumor control. The last 2 procedures permit a low morbidity. In the actual TNM classification it was recently introduced a definition of a "pN0" patient based on sentinel node biopsy. New target volumes are defined for adjuvant radiotherapy or lymphatic basins could be spared from unnecessary irradiation.

The sentinel node concept seems to revolutionize the treatment of early breast cancer. Biopsy of the sentinel node is a highly accurate, minimally invasive method of staging patients and can substantially reduce the morbidity and costs of treatment by avoiding unnecessary complete axillary lymph node dissection. The procedure may lead to a more justifiable approach to adjuvant therapy strategies with low complication rates. The identification of the individual lymphatic flow pattern would permit the irradiation of the individual locoregional lymphatic basin.