Background: Previous trials have demonstrated the safety of omitting axillary lymph node dissection (ALND) in cT1-3, cN0 breast cancer patients with one to two sentinel lymph node (SLN) involvement undergoing breast-conserving surgery (BCS). However, their applicability to mastectomy patients – who do not routinely receive chest wall irradiation – remains unclear. This study aimed to evaluate whether omitting ALND is noninferior to completion of ALND among patients undergoing mastectomy. Methods: We emulated a target multicenter, nonblinded, noninferiority trial to compare sentinel lymph node biopsy only (SLNB only) and SLNB plus ALND using combined prospective and retrospective cohorts. Eligible patients had cT1-3, cN0 breast cancer with one to two SLN metastases. The primary endpoint was 5-year recurrence-free survival (RFS). Noninferiority was defined as a hazard ratio (HR) of less than 1.54 comparing the SLNB-only group to the ALND group. This study was prospectively registered with Chictr.org.cn. Results: Among 1090 included patients, 438 (40.2%) received SLNB only and 652 (59.8%) received ALND. After a median follow-up of 4.74 years, 88 patients experienced recurrence or died. The estimated 5-year RFS was 91.5% (95% CI, 89.1–93.9) in the SLNB only group and 91.8% (95% CI, 88.7–95.1) in the ALND group (HR = 0.83; 95% CI, 0.51–1.33; P noninferiority = 0.005). Primary findings were consistent across subgroups and sensitivity analyses. Conclusion: Results of this targeted trial revealed that ALND can be omitted in patients undergoing mastectomy with clinically node-negative, cT1-3 invasive breast cancer who had one to two SLN metastases. These findings further inform the de-escalation of axillary surgery in breast cancer management.
Xie et al. (Thu,) studied this question.