Trade-offs associated with axillary lymph node dissection: Implications of the eligibility versus enrollment in ACOSOG Z0011.

Abstract

151 Background: Results from ACOSOG Z0011 suggest that axillary lymph node dissection (ALND) may not be necessary for patients following positive sentinel lymph node biopsy (SLNB). Concerns have been raised regarding the generalizability of this trial, given the low-risk patient population. It is uncertain whether a subgroup who would have been eligible for ACOSOG Z0011 but were not adequately represented in the study may still benefit from ALND. Methods: We constructed a decision analysis using a Monte Carlo model to simulate axillary recurrence (ALR) risk, lymphedema, and quality of life of women age 45, 55, and 75 y/o with stage II cancers following breast conserving surgery (BCS) with positive SLNB who were then treated with either ALND and whole-breast radiation (BRT) or BRT alone. Women were divided into two risk groups: those with a risk of residual nodal involvement of 30-60% (high risk); and those with a risk less than 30% (low risk, similar to the Z0011 patients). Probabilities and utilities for health states were derived from previous studies. Results: BRT alone resulted in improved quality-adjusted life expectancy (QALE) in the low-risk group, while ALND with BRT resulted in improved QALE in the high-risk group. Overall survival (OS) was similar at 5 years with both treatment strategies in both groups but was superior with ALND at 20 years in the high risk group (Table). Differences in outcomes decreased with increasing age. In the low-risk group, sensitivity analysis showed BRT alone is preferred unless the ALR risk with BRT is greater than 1.6% or the lymphedema risk with ALND is less than 10%. In the high-risk group, ALND with BRT is the preferred strategy unless the ALR risk with BRT is less than 2.3%. Conclusions: Patients who would have been eligible for ACOSOG Z0011 but are at higher risk of having residual nodal disease following BCS and positive SLNB may benefit from ALND plus BRT rather than BRT alone. [Table: see text]