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Breast

Breast Parallel Session 2

17: Omission of Routine Frozen Section Among Clinically Node-Negative Patients Having Upfront Mastectomy Avoids Unnecessary Axillary Treatment

Saturday, March 23, 2024
8:50am – 9:00am ET
Location: C101
Disclosure(s):
Rachel Sargent, MD: No financial relationships to disclose
Introduction: Randomized trials established the safety of postmastectomy radiation (PMRT)/regional nodal irradiation as an alternative to axillary dissection (ALND) for cN0 patients having upfront mastectomy with 1-2 positive sentinel lymph nodes (+SLNs). Intraoperative SLN evaluation often leads to ALND for patients with limited nodal disease, who may be adequately treated with PMRT alone. In 1/2022, we adopted a policy omitting routine frozen section for cT1-3N0 patients having upfront mastectomy and sought to examine the impact on axillary treatment.


Methods: Consecutive patients with cT1-3N0 breast cancer treated with upfront mastectomy from 1/2022-7/2023 were identified from a prospectively maintained database. Intraoperative SLN evaluation was omitted throughout the study period, except for N = 9 cases per surgeon discretion, which were excluded from the cohort. ALND was indicated for ≥ 3 +SLNs or 1-2 +SLNs not meeting institutional PMRT criteria. We evaluated rates of ALND and PMRT following policy adoption.


Results: From 1/2022-7/2023, 623 cT1-3N0 patients had upfront mastectomy with SLN biopsy. Median age was 51 years; most tumors were cT1-2 (96%), HR+/HER2- (83%), of ductal histology (71%), and moderately differentiated (58%), and 73% had no lymphovascular invasion (LVI). 451 (72%) patients were pathologically node negative, 45 (7%) had micrometastases only, and 127 (20%) had macrometastases: 98 (16%) had 1-2 +SLNs while 29 (5%) had ≥ 3 +SLNs. Overall, 4.7% (n = 29) patients had completion ALND. Patients who had ALND had larger tumors, and more often had lobular histology and LVI. Among pN0 and pN1mic patients (n = 496), none had ALND and 27 (5%) had PMRT. 86 of 98 patients (88%) with 1-2 +SLNs had PMRT and no further surgery, 8 (8%) had ALND due to no initial PMRT indication, of which 2 (2%) patients then met PMRT criteria based on additional nodal pathologic data, and 4 (4%) had neither. Among those with ≥ 3 +SLNs (n = 29), 21 (72%) had both ALND+PMRT, while 8 (27.6%) had PMRT only or neither treatment, per patient preference/physician discretion (Table). Overall, return to the OR for ALND was indicated in 39 of 623 (6.2%) patients for ≥ 3 +SLNs or 1-2 +SLNs without PMRT indication.


Conclusions: Only 5% of cN0 patients who had SLN frozen section omitted at upfront mastectomy had completion ALND, and receipt of ALND+PMRT in patients with involvement of 1-2 nodes was rare, occurring in < 1% of the cohort. Axillary management is optimized by routine omission of frozen section among cT1-3N0 patients having upfront mastectomy.

Learning Objectives:

  • Upon completion, participants will be able to describe rates of axillary dissection among cN0 patients who are treated without frozen section at the time of upfront mastectomy.
  • Upon completion, participants will be able to describe the rarity of axillary overtreatment with this approach, and resultant reduction in surgical morbidity.
  • Upon completion, participants will be able to review the benefits of and consider routine omission of frozen section among patients with cN0 in practice.