V4: Can We Forego Sentinel Lymph Node Biopsy in Women with Early-stage Special Histologic Subtype Breast Cancer?

Tuesday, March 1, 2022

5:01 PM – 5:04 PM CST

Location: Zoom Meeting

Virtual Poster Presenter(s)

Nicole Knape

Medical Student
UNC School of Medicine

Disclosure: Disclosure information not submitted.

Participants should be aware of the following financial/non-financial relationships:

Nicole Knape: Disclosure information not submitted.

Introduction: Breast cancer has significant biologic heterogeneity, increasingly influencing treatment decisions. We hypothesized that in postmenopausal women (≥ 50 years) with clinical T1-T2, N0, hormone receptor positive (HR+), Her2- breast cancers of special histologic subtype (mucinous, tubular, cribriform, papillary), information gained from sentinel lymph node biopsy (SLNB) may not change adjuvant treatment recommendations when Oncotype Dx Recurrence Score (ODX RS) is available.

Methods:

We used the National Cancer Database to construct a retrospective cohort of women aged ≥ 18 with cT1-T2 N0 invasive special histologic subtype breast cancer. We calculated the frequency of pathologic N stages by HR/HER2 status. In women with HR+/Her2- disease, we measured the distribution of ODX RS across special histology subtypes by pathologic nodal status and frequency of chemotherapy use among women aged ≥ 50 by ODX RS and pathologic N stage.

Results:

In women with cN0 special histologic subtype breast cancer, the likelihood of pathologic N2 or N3 disease is extremely low (0.9% of HR+/Her2-, 4.1% of HR-Her2+, 0.2% of HR+Her2-, and 0.6% of HR-Her2-). Among patients with HR+/Her2- disease, 4.5% (181/14,002) had pathologically positive sentinel lymph nodes, (4.3% (609/14,002) N1 and 0.2% (32/14,002) N2/N3). Among women aged ≥ 50 with HR+/Her2- special histologic subtype breast cancer, there was low prevalence of high ODX RS ≥ 26 (7% (197/2868)). In women aged ≥ 50 with pathologic N1 disease, high ODX RS is rare, (tubular (0/28), cribriform (0/18), papillary 4% (1/26), mucinous 11% (12/113)), but there remains biologic variability. In women ≥ 50 who were pathologically N0, adjuvant chemotherapy was administered in 2%, 10%, and 74% of women with low, intermediate, and high Oncotype scores respectively and in 6%, 24%, and 92% in pathologically N1 patients.

Conclusions:

Our study suggests that SLNB could potentially be omitted in Z0011/RxPonder eligible postmenopausal women with cT1-T2 N0 HR⁺/Her2^-, special histologic subtype breast cancer when ODX RS is available, given the extremely low rate of pathologic N2/N3 disease.

Learning Objectives:

Define the likelihood of N2/N3 disease in patients with special histologic subtype breast cancer
Demonstrate understanding of the utility of Oncotype Dx testing in predicting biologic behavior in breast cancers of. special histologic subtype.
Define a group of breast. cancer patients with special histologic subtype cancers in whom sentinel node biopsy may be omitted when Oncotype testing is available.