Sentinel lymph node biopsy in breast cancer

The concept of sentinel lymph node (SLN) biopsy in breast cancer patients is simple, attractive and rapidly emerging as a new standard of care. Several aspects of the technique of lymphatic mapping, case selection, pathologic analysis and the finding of micrometastases, and the accuracy of the technique are important subjects of study and debate in the literature and will be discussed in this review. High identification rates can be attained by the use of both radioguided and blue dye lymphatic mapping. Intradermal injection of tracers has reported to be successful, suggesting that dermal and parenchymal lymphatics drain to the same SLN. Extra axillary drainage is only seen after peri- or intratumoural injection. SLN biopsy is most widely used for both palpable and non-palpable T1 and T2 tumours, and limited experience exists for other indications. Accuracy is high only in experienced hands. The impact of failure of the procedure on regional disease control and survival will be assessed in a trial of the NSABP (National Adjuvant Breast and Bowel Project). The influence of a positive SLN biopsy with and without axillary dissection on survival and local control will be studied in trials of the BASO (British Association of Surgical Oncology), ACOSOG (American College of Surgeons Oncology Group) and EORTC (European Organisation for Research and Treatment of Cancer). These phase III trials and related studies on the importance of micrometastases in the SLN will give new insights in the safety of the SLN procedure and in the importance of treatment of regional lymph nodes in relation to local disease control and survival.