The learning curve and sentinel node biopsy

The ability of sentinel node biopsy (SNB) to replace axillary node dissection for accurate breast cancer staging is absolutely dependent on the consistent and accurate determination and removal of the "true" sentinel node. There are a wide variety of variables that affect the ability of the physician to achieve this goal. One important and potentially controllable variable is physician training and competence to employ the available techniques successfully. There is a large diversity of opinion regarding the minimum number of cases required under supervision prior to independent utilization of the technique but there are data to support at least 20 cases done in conjunction with axillary dissection or under direct supervision.

Data from single institution and multicenter trials are reviewed and the learning curves are described. An overview of surgical education methods, testing, and credentialing is also addressed.

A review of single institution series show that the false negative rate and identification rates vary considerably. In all cases where authors published a second series success rate improved compared with their initial series. Of the four multicenter trials only two can provide reliable learning curves and these have shown a decrease in the false negative rate to < or = 5% after 20 to 30 procedures are performed.

There are data to show that there is a definite learning curve for SNB that cannot be ignored. It is possible that other factors, (ie, a skin injection with technetium-99, Sappeys plexus injection, and mentoring) could decrease this learning curve but until compelling evidence to suggest otherwise is available, surgeons should obtain a minimum experience of 20 cases.