Abstract P3-01-01: Management of the axilla in metaplastic breast carcinoma

Abstract

Abstract Background Metaplastic breast cancer (MBC), characterized by a mixture of epithelial, squamous or mesenchymal elements and a usually triple-negative (TN) phenotype, accounts for <1% of breast cancer diagnoses. MBC has a poor prognosis with frequent distant spread, but, paradoxically, a lower than expected rate of nodal positivity (6 to 40%). Due to its rarity there is little data on how best to evaluate and manage the axilla in women with these tumors. Thus we undertook this study to evaluate axillary management and oncologic outcomes. Methods With IRB approval, we identified adult patients diagnosed with MBC at our institution from 2001 to 2011 from our prospective surgical pathology database. Patient, pathology, imaging, treatment and outcome data were obtained from electronic medical record, tumor registry, pathology slide and imaging review. Median follow-up for surviving patients was 66 months. Statistical analyses were performed using JMP 10.0 software. Results We identified 41 MBC patients, median age 60 years (range 33-89 years), with a median tumor size of 2.7 cm; 33 (80%) were TN. 23 patients (56%) had a preoperative axillary ultrasound (AUS): 9 (39%) showed at least one suspicious axillary lymph node (LN) of whom 6 had a preoperative fine needle LN biopsy (FNA) of which 3 were positive for metastasis. 6 patients, including the 3 LN+ on FNA, had neoadjuvant chemotherapy (NAC). Operation included axillary dissection (ALND) in 14, sentinel LN biopsy (SLNB) in 23, and SLNB followed by ALND in 1, while 3 patients had no axillary surgery. 10 patients were LN+ at operation. Among 22 patients who had both an AUS and axillary surgery, AUS had a sensitivity of 100% and specificity of 78%. Patient and tumor variables in association with pathologic LN status are summarized in the table. LN positivity correlated with increasing tumor size, T stage, grade and angiolymphatic invasion. 16 patients recurred, most with distant disease (10/16, 63%), although there was a solitary axillary recurrence 8 months after a negative SLNB in one patient who did not have a preoperative AUS. Thus the accuracy of SLNB was 96% (23/24) overall, but among those without preoperative AUS, 1/7 (14%) SLNBs were falsely negative. 5-year disease-free and breast cancer-specific survival estimates were 49% and 63%. LN- N=28 (74%)LN+ N=10 (26%)p-valueSize, median (IQR), cm2.7 (1.6-4.6)6.6 (2.5-16.5)0.001T stage 0.03T19 (100%)0 (0%) T214 (78%)4 (22%) T33 (60%)2 (40%) T42 (33%)4 (67%) Grade 0.04Low6 (16%)0 (0%) Intermediate/High22 (58%)10 (26%) Estrogen Receptor 0.61Positive (>1%)5 (71%)2 (29%) Negative (<1%)23 (74%)8 (26%) Angiolymphatic Invasion 0.002No26 (87%)4 (13%) Yes2 (25%)6 (75%) Dominant Histology 0.65Adenosquamous2 (100%)0 (0%) Matrix producing4 (80%)1 (20%) Spindle cell14 (74%)5 (26%) Squamous*8 (67%)4 (33%) *any squamous component Conclusion Our study is the first to specifically address AUS and SLNB for patients with metaplastic breast cancer. AUS had 100% sensitivity and 78% specificity, while one patient without a preoperative AUS had a falsely negative SLNB. Further, AUS with FNA of suspicious LNs was useful for staging at the time of diagnosis and informing treatment. We recommend this approach for patients with MBC. Citation Format: Murphy BL, Fazzio RT, Hoskin TL, Glazebrook KN, Keeney MG, Habermann EB, Hieken TJ. Management of the axilla in metaplastic breast carcinoma [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-01.