Hypothesis: Performance of sentinel node biopsy (SNB) instead of full axillary lymph node dissection (ALND) by inexperienced surgeons will lead to understaging of some women with breast cancer and increased costs.
Design: A decision analysis model was used to investigate the implications of SNB vs. full ALND during the learning phase (60-80 procedures). This model simulates a randomized trial of 10000 women in each arm. Data regarding the learning curve were obtained from published series.
Main outcome measures: Percentage of women with inaccurate staging of their breast cancer, overall survival, quality-adjusted survival, and potential costs of SNB vs ALND.
Results: Performance of SNB instead of ALND results in inability to locate a sentinel node in 38% of attempts during the learning phase (compared with 10% in later cases) and understaging in 12% of patients during the learning phase (compared with 0% in later cases). This understaging is associated with a small decrement in survival (1%-2%) and an increased risk of axillary recurrence. Sentinel node biopsy is cost-effective only when the ability to detect sentinel nodes exceeds 80%; and the cost of SNB is less than 50% of the cost of ALND.
Conclusions: To ensure accurate staging of patients with breast cancer, all surgeons should perform full ALND while learning SNB techniques. Only after documentation of accuracy of SNB (sensitivity >90%) should full ALND be omitted for women with negative sentinel nodes.