Total Tumor Load to assist in the decision for additional axillary surgery in the positive sentinel node breast cancer patients

Abstract

The Total Tumor Load (TTL) concept has been demonstrated to accurately predict the status of the non-sentinel lymph nodes (NSLN) in breast cancer patients. In 2019, our center implemented the TTL cut-off of 30,000 CK19 mRNA copies/uL as sole criterion for deciding on performing ALND. This retrospective, unicentric, study analyzed 87 cT1-3N0 breast cancer patients treated consecutively in a period of two years and aimed to evaluate the performance of this criterion. Secondary objectives included the comparison of the criterion versus our previous Clinical Decision Rule (CDR) versus ACOSOG Z0011 criteria for avoiding an ALND in proportion of patients spared an ALND and in proportion of patients left with a surgically untreated metastasized axilla. An interim analysis revealed new TTL cut-offs for deciding on performing an ALND. The 30,000 CK19 mRNA copies/uL criterion yielded an area under the ROC Curve (AUC) of 0.849, a false positive (FP) rate of 30.1% and a positive predictive value (PPV) of 38.9%. The 30,000 CK19 mRNA copies/uL criterion spared 58.6% of the patients an ALND versus 41.4% with CDR versus 73.6% with Z0011 and left 0.0% patients with a surgically untreated metastasized axilla versus 21.4% with CDR versus 42.9% with Z0011. The new TTL cut-off of 260,000 CK19 mRNA copies/uL for deciding on an ALND yielded an AUC of 0.753, a FP rate of 13.7% and a PPV of 47.4%. This new criterion spared 78.2% of the study sample an ALND and left 35.7% of metastasized axillae surgically untreated. This study emphasizes the need to find a new balance between locoregional control and the morbidity associated with Berg levels I+II axillary lymph node dissection.