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Surgical Management Of The Axilla Following Neoadjuvant Endocrine Therapy
*Brenna M Murphy, *Tanya L Hoskin, *Amy C Degnim, *Judy C Boughey, Tina J Hieken
Mayo Clinic, Rochester, MN

Objective: Based on randomized clinical trial data, including ACOSOG Z0011, there has been a marked recent de-escalation of axillary surgery in selected breast cancer patients with low volume axillary disease treated with a surgery first approach. However, these studies did not enroll patients treated with neoadjuvant endocrine therapy (NET), an approach increasingly used to test response in hormone receptor-positive breast cancer and determine the need for chemotherapy. As little evidence exists to guide axillary surgery for patients treated with NET, we aimed to evaluate the extent of axillary surgery among NET patients in a high-volume contemporary practice.
Methods: With IRB approval we identified patients with invasive breast cancer treated with NET 10/2008-11/2019 from our prospective surgical registry. Patients presenting with stage IV disease or recurrence were excluded. Statistical analyses were performed using chi-square, Fisher's exact and Wilcoxon rank-sum tests.
Results: We identified 209 invasive breast cancers in 200 patients (median age 66 years); 87 had breast-conserving surgery (BCS) and 122 mastectomy. 85 patients (41%) were clinically node-positive with 6 (7%) pN0 following NET; overall 13 (15%) underwent sentinel lymph node biopsy (SLNB), 26 (31%) SLNB+axillary dissection (ALND) and 46 (54%) ALND. Of 124 clinically node-negative patients (9%) had no axillary operation while 81/113 (72%) who did have axillary surgery were pN0; axillary operation was SLNB in 96 (85%), SLNB+ALND in 16 (14%) and ALND in 1 (1%). Axillary operation stratified by breast operation in relation to patient and tumor variables is summarized in the table. Among patients with 1 or 2 positive nodes, SLNB alone was performed more frequently in BCS than mastectomy patients (65% vs 24%, p=0.002). With 36 months median follow-up, no regional nodal recurrences were observed.
Conclusions: We observed de-escalation of axillary surgery among patients with one or two positive nodes following NET, particularly among BCS patients, and no nodal recurrences. These data suggest NET patients might be managed similarly to patients treated with a surgery first approach.

Patient and Tumor Variables Stratified by Extent of Axillary Surgery and Breast Operation
BCS Patients treated with axillary surgery (n = 79)
SLN only
(N=51)
SLN & ALND
(N=11)
ALND only
(N=17)
p value
Age, Median (IQR)66 (62-72)66 (53-71)70 (57-73)0.43
Presentation0.08
Palpable Mass22 (43.1%)6 (54.5%)14 (82.4%)
Abnormal Imaging21 (41.2%)3 (27.3%)2 (11.8%)
cN category<0.001
cN042 (82.4%)4 (36.4%)0 (0.0%)
cN+9 (17.6%)7 (63.6%)17 (100.0%)
Grade0.96
I (Well Differentiated)16 (32.7%)3 (30.0%)5 (29.4%)
II (Moderately Differentiated)30 (61.2%)6 (60.0%)10 (58.8%)
III (Poorly Differentiated)3 (6.1%)1 (10.0%)2 (11.8%)
Tumor size, cm, median (Q1-3)1.9 (1.5,2.6)2.4 (1.6,3.1)1.7 (1.3,2.4)0.33
pN category0 (0, 1)3 (2, 6)2 (1, 5)<0.001
N033 (64.7%)0 (0.0%)2 (11.8%)
N117 (33.3%)7 (63.6%)9 (52.9%)
N21 (2.0%)3 (27.3%)3 (17.6%)
N30 (0.0%)1 (9.1%)3 (17.6%)
Nodal metastasis size, mm, median (Q1-3)4.5 (2.1, 11)11 (5, 18)12 (8, 26)0.03
Extranodal extension (pN+), present6 (33.3%)4 (36.4%)6 (40.0%)
Number of LNs positive, median (Q1-3)0 (0, 1)3 (2, 6)2 (1, 5)<0.001
Mastectomy Patients treated with axillary surgery(n = 119)
Age, median (Q1-3)66.5 (55, 71)61 (53, 67)63.5 (54, 72)0.33
Presentation0.01
Palpable Mass26 (44.8%)23 (74.2%)18 (60.0%)
Abnormal Imaging25 (43.1%)5 (16.1%)5 (16.7%)
cN category<0.001
cN054 (93.1%)12 (38.7%)1 (3.3%)
cN+4 (6.9%)19 (61.3%)29 (96.7%)
Grade0.12
I (Well Differentiated)27 (49.1%)8 (26.7%)11 (37.9%)
II (Moderately Differentiated)27 (49.1%)21 (70.0%)15 (51.7%)
III (Poorly Differentiated)1 (1.8%)1 (3.3%)3 (10.3%)
Tumor size, cm, median (Q1-3)2.5 (1.4, 5.9)2.9 (2.3, 4.8)3.7 (2.5, 6.8)0.21
pN category<0.001
N051 (87.9%)0 (0.0%)1 (3.3%)
N16 (10.3%)19 (61.3%)13 (43.3%)
N21 (1.7%)7 (22.6%)9 (30.0%)
N30 (0.0%)5 (16.1%)7 (23.3%)
Nodal metastasis size, mm, median (Q1-3)7.5 (5, 18)7 (5, 10)13 (8, 22)0.02
Extranodal extension (pN+), present0 (0.0%)22 (75.9%)21 (80.8%)<0.001
Number of LNs positive, median (Q1-3)0 (0, 0)2 (1, 8)4 (2, 10)<0.001


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