Background: With increasing frequency, breast cancer patients and clinicians are questioning the need for completion axillary lymph node dissection (ALND) in the setting of a positive sentinel lymph node (SLN). We previously developed a nomogram to estimate the likelihood of residual disease in the axilla after a positive SLN biopsy result. In this study, we compared the predictions of clinical experts with those generated by the nomogram and evaluated the ability of the nomogram to change clinicians' behavior.
Methods: Pathologic features of the primary tumor and SLN metastases of 33 patients who underwent completion ALND were presented to 17 breast cancer specialists. Their predictions for each patient were recorded and compared with results from our nomogram. Subsequently, clinicians were presented with clinical information for eight patients and asked whether they would perform a completion ALND before and after being presented with the nomogram prediction.
Results: The predictive model achieved an area under the receiver operating characteristic curve of .72 when applied to the test data set of 33 patients. In comparison, the clinicians as a group were associated with an area under the receiver operating characteristic curve of .54 (P < .01 vs. nomogram). With regard to performing a completion ALND, providing nomogram results did not alter surgical planning.
Conclusions: Our predictive model seemed to substantially outperform clinical experts. Despite this, clinicians were unlikely to change their surgical plan based on nomogram results. It seems that most clinicians can improve their predictive ability by using the nomogram to predict the likelihood of additional non-SLN metastases in a woman with a positive SLN biopsy result.