Trends in Axillary Lymph Node Dissection After Mastectomy Among Patients With Limited Nodal Burden.

IMPORTANCE

Current practices in axillary treatment for patients with breast cancer who receive a mastectomy for node-positive disease are unknown. For patients who receive postmastectomy radiotherapy (PMRT), the addition of axillary lymph node dissection (ALND) may result in significant overtreatment.

OBJECTIVES

To evaluate trends in axillary treatment for patients with limited nodal metastases who receive a mastectomy and identify factors that can be targeted to reduce axillary overtreatment.

DESIGN, SETTING, AND

PARTICIPANTS

A retrospective cohort study was conducted of patients identified from the National Cancer Database who received a diagnosis of breast cancer from January 1, 2012, to December 31, 2021. Patients included were women aged 18 years or older with clinical (c) T1-T2N0 breast cancer who underwent mastectomy with axillary staging with sentinel lymph node biopsy (SLNB) and/or ALND and had 1 to 2 positive lymph nodes. Patients who received neoadjuvant therapies were excluded. Statistical analysis was performed from December 2023 to July 2024.

EXPOSURE: Axillary management based on ALND and PMRT receipt: (1) ALND alone, (2) PMRT alone, (3) both ALND and PMRT, and (4) neither ALND nor PMRT.

MAIN OUTCOMES AND MEASURES: Axillary management strategies were evaluated, and clinicopathologic characteristics based on treatment type were compared with multivariable analysis.

RESULTS

In total, 62 332 patients were included (median age, 58 years [IQR, 48-68 years]; 82.2% with Charlson-Deyo comorbidity score 0). The proportion of patients who received ALND alone decreased from 47.1% to 17.6% from 2012 to 2021, while the percentage of patients who received PMRT alone increased from 9.8% to 36.8%. Overall, 21.3% of patients received treatment with both ALND and PMRT, with little change over time (from 21.7% in 2012 to 17.7% in 2021). Most patients (88.4%) who received both PMRT and ALND underwent ALND at the same operation as SLNB. Younger age (odds ratio [OR] per year increase, 0.98 [95% CI, 0.98-0.98]; P < .001), high-grade tumors (grade 2: OR, 1.18 [95% CI, 1.09-1.29]; P < .001; grade 3: OR, 1.34 [95% CI, 1.22-1.48]; P < .001), presence of lymphovascular invasion (OR, 1.26 [1.19-1.33]; P < .001), and larger tumor size (cT2 tumors compared with cT1: OR, 1.10 [95% CI, 1.03-1.17]; P = .004; upstaging to pathologic T3 tumors: OR, 2.29 [95% CI, 1.15-4.99]; P = .03) were associated with increased likelihood of concurrent treatment with ALND and PMRT.

CONCLUSIONS AND RELEVANCE: In this retrospective cohort study of patients with breast cancer who received a mastectomy, a substantial proportion of those with 1 to 2 positive lymph nodes were treated with both ALND and PMRT. Delaying the decision for ALND until after multidisciplinary input may reduce overtreatment.