Background: The purpose of this study was to prospectively evaluate the combined use of The Memorial Sloan Kettering Cancer Center nomogram and Tenon score to select, in patients with metastatic sentinel lymph node (SN), those at low risk of metastatic non-SN for whom additional axillary lymph node dissection (ALND) could be avoided.
Methods: From January 2011 to July 2012, a prospective non-interventional nationwide study was conducted (NCT01509963). We sought to identify the false reassurance rate (FRR, a negative test result is false) in patients with both a ⩽10% probability of metastatic non-SN with the MSKCC nomogram and a Tenon score ⩽3.5 (low risk): the proportion of patients with metastatic non-SN at additional ALND. Our hypothesis was that these patients would have a FRR⩽5%.
Results: Data on 2822 patients with breast cancer from 53 institutions were prospectively recorded. At least one SN was metastatic (isolated tumour cells, micro- or macrometastases) in 696 patients (24.7%). Among patients with ALND and complete data to calculate combined risk (n=504), 67 and 437 patients had low and high combined risk, respectively. Patients at low risk had less ALND (47%) compared to patients at high risk (P<0.001). This study did not meet its primary objective because the FRR in patients with low risk was 16.4% (11 out of 67) (95% confidence interval (CI): 9.7-23.1%). In the high-risk group, 33.9% (148 out of 437) (95% CI: 29.6-38.4%) had non-SN metastases (P=0.004).
Conclusions: In this controlled prospective study, metastatic SN patients with both a ⩽10% probability of metastatic non-SN with the MSKCC nomogram and a Tenon score ⩽3.5 failed to identify patients at low risk of metastatic non-SN when completion ALND was not systematic.