Sentinel lymph node (SLN) biopsy is now a standard component of the treatment of many melanomas, and its use is accepted as routine.1,2 So routine, in fact, that the revolutionary nature of its beginning is little remembered. This is appropriate as the technique and the clinical data supporting its use are now both broad and deep. However, even with our familiarity with the procedure, it is important to remember that the technique requires skill and coordination of multiple disciplines and that appropriate selection of candidates for SLN biopsy is necessary. The impact of SLN biopsy has now spread from melanoma to breast cancer, and may become more common in other solid tumors. The benefits it has produced for melanoma patients around the world including more accurate staging and less morbid treatment of regional lymph nodes are remarkable and will ensure that SLN biopsy will continue to be a vital component of melanoma treatment into the future.
The history of SLN biopsy is, in some respects, quite old. Indeed, since the apparent orderly progression of cancer from primary tumor to lymph nodes and then subsequently to distant sites has been observed for centuries, the concept of determining a reliable means of mapping that progression is not new. For example, Rudolph Virchow, father of modern pathology, noted drainage of carbon pigment from a skin tattoo to specific lymph nodes.3 Leonard Brathwaite, a British surgeon, examined lymphatic drainage from the omentum using blue dye and described a "gland sentinel" at the root of the small bowel mesentery that received the drainage.4
Gould et al5 described a "sentinel" node located close to the junction of the facial and jugular veins that was the drainage point for tumors of the parotid gland. Cabanas6 described a "sentinel" node located adjacent to the superficial epigastric vein at the level of the junction of the femoral head and ascending pubic ramus that received drainage from tumors of the penis. He postulated that this node would provide information representative of the tumor status of the entire nodal basin.
However, all of these concepts were founded on the assumption that there was a consistent, anatomically determined lymph node that would act as sentinel. None proved to be a reliable indicator of nodal staging that could be applied more generally. What was required was a procedure that took into account functional information in determining the drainage pattern of a primary tumor. This accomplishment was not achieved until the 1980s, and was arrived via another route of investigation.
In melanoma, the subject of treatment of clinically negative regional lymph nodes has been controversial at least since "anticipatory gland excision" was proposed by Herbert Snow7 at the end of the 19th century. Over most of the 20th century, there were proponents and opponents of elective regional nodal dissection, ...