The extent of extracapsular extension may influence the need for axillary lymph node dissection in patients with T1-T2 breast cancer.
BACKGROUND
Whether extracapsular extension (ECE) of tumor in the sentinel lymph node (SLN) is an indication for axillary lymph node dissection (ALND) in patients managed by American College of Surgeons Oncology Group Z0011 criteria is controversial. Here we examine the correlation between ECE in the SLN and disease burden in the axilla.


METHODS
Patients meeting Z0011 clinicopathologic criteria (pT1-2, cN0 with <3 positive SLNs) were selected from a prospectively maintained database (2006-2013). Chart review documented the presence and extent of ECE. Neoadjuvant chemotherapy patients were excluded. Comparisons were made by presence and extent (≤2 vs. >2 mm) of ECE.


RESULTS
Of 11,730 patients, 778 were pT1-2, cN0 with <3 positive SLNs without ECE, and 331 (2.8 %) had ECE. Of these, 180 had ≤2 mm and 151 had >2 mm of ECE. Patients with ECE were older (57 vs. 54 years; p = 0.001) and had larger (2.0 vs. 1.7 cm; p < 0.0001), multifocal (p = 0.006), hormone receptor-positive tumors (p = 0.0164) with lymphovascular invasion (p < 0.0001). Presence and extent of ECE were associated with greater axillary disease burden; 20 and 3 % of patients with and without ECE, respectively, had ≥4 additional positive nodes at completion ALND (p < 0.0001), and 33 % of patients with >2 mm ECE had ≥4 additional positive nodes at completion ALND, compared with 9 % in the <2 mm group (p < 0.0001). On multivariate analysis, >2 mm of ECE was the strongest predictor of ≥4 positive nodes at completion ALND (odds ratio 14.2).


CONCLUSIONS
Presence and extent of ECE were significantly correlated with nodal tumor burden at completion ALND, thus suggesting that >2 mm of ECE may be an indication for ALND or radiotherapy when applying Z0011 criteria to patients with metastases in <3 SLNs. ECE reporting should be standardized to facilitate future studies.
Breast Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Jessica
J
Gooch
Tari A
TA
King
Anne
A
Eaton
Lynn
L
Dengel
Michelle
M
Stempel
Adriana D
AD
Corben
Monica
M
Morrow
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D015412:Mastectomy, Segmental; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy; D047368:Tumor Burden; D055815:Young Adult