Ann Surg Oncol
(published online)

Changes in Surgical Management of the Axilla Over 11 Years – Report on More Than 1500 Breast Cancer Patients Treated with Neoadjuvant Chemotherapy on the Prospective I-SPY2 Trial

Boughey JC, Yu H, Dugan CL, Piltin MA, Postlewait L, Son JD, Edmiston KK, Godellas CV, Lee MC, Carr MJ, Tonneson JE, Crown A, Lancaster RB, Woriax HE, Ewing CA, Chau HS, Patterson AK, Wong JM, Alvarado MD, Yang RL, Chan TW, Sheade JB, Ahrendt GM, Larson KE, Switalla K, Tuttle TM, Tchou JC, Rao R, Tamirisa N, Singh P, Gould RE, Terando A, Sauder C, Hewitt K, Chiba A, Esserman LJ, Mukhtar RA.

Background: Axillary surgery after neoadjuvant chemotherapy (NAC) is becoming less extensive. We evaluated the evolution of axillary surgery after NAC on the multi-institutional I-SPY2 prospective trial.

Methods: We examined annual rates of sentinel lymph node (SLN) surgery with resection of clipped node, if present), axillary lymph node dissection (ALND), and SLN and ALND in patients enrolled in I-SPY2 from January 1, 2011 to December 31, 2021 by clinical N status at diagnosis and pathologic N status at surgery. Cochran-Armitage trend tests were calculated to evaluate patterns over time.

Results: Of 1578 patients, 973 patients (61.7%) had SLN-only, 136 (8.6%) had SLN and ALND, and 469 (29.7%) had ALND-only. In the cN0 group, ALND-only decreased from 20% in 2011 to 6.25% in 2021 (p = 0.0078) and SLN-only increased from 70.0% to 87.5% (p = 0.0020). This was even more striking in patients with clinically node-positive (cN+) disease at diagnosis, where ALND-only decreased from 70.7% to 29.4% (p < 0.0001) and SLN-only significantly increased from 14.6% to 56.5% (p < 0.0001). This change was significant across subtypes (HR-/HER2-, HR+/HER2-, and HER2+). Among pathologically node-positive (pN+) patients after NAC (n = 525) ALND-only decreased from 69.0% to 39.2% (p < 0.0001) and SLN-only increased from 6.9% to 39.2% (p < 0.0001).

Conclusions: Use of ALND after NAC has significantly decreased over the past decade. This is most pronounced in cN+ disease at diagnosis with an increase in the use of SLN surgery after NAC. Additionally, in pN+ disease after NAC, there has been a decrease in use of completion ALND, a practice pattern change that precedes results from clinical trials.

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