Prevalence of extracapsular extension in metastatic sentinel lymph nodes in breast cancer

Introduction: Axillary lymph node involvement is recognized as a key prognostic factor for invasive breast cancer. Retrospective analyzes have shown that extracapsular extension (ECE) is correlated with negative prognostic factors in this neoplasia. Objective: to evaluate the measurement of ECE and its relationship with the number of affected non-sentinel lymph nodes, as well as to investigate the association between ECE with other clinical and pathological prognostic factors. Methods: This is a cross-sectional observational study carried out from January 2015 to June 2019, at the Breast Surgical Oncology service of Liga Contra o Cancer (LIGA), in Natal, Brazil. A total of 150 patients were included in the study and were divided into three groups: absence of ECE, ECE less than or equal to 2 mm and ECE greater than 2 mm. Results: The mean age was 58 years for the group with ECE and 57 years for the group without ECE. Most of the patients were mixed race (66.7%), had no family history of breast cancer (64%) and underwent quadrantectomy (64.5%). Regarding the characteristics of the disease, most presented a histological report compatible with Invasive Carcinoma of the non-special type (IC NST) (87.5%), histological grade II (52.7%), negative Lymphovascular invasion (LVI) (52.7%), Tumor Size T1 (<2.0 cm) (52%) and Luminal B molecular subtype (36.7%). Regarding sentinel lymph nodes: 103 patients (68.7%) had ECE and 1 positive sentinel lymph node was identified in most cases. There was a statistically significant association between the presence of ECE and of being mixed race (p = 0.03), between ECE and LVI (p = 0.05) and between ECE and a greater number of positive nonsentinel lymph nodes (p 0.001). Conclusion: Our study showed that ECE 2 mm is associated with increased axillary nodal load compared to groups without ECE and ECE <= 2 mm in sentinel node biopsy in patients who met the Z0011 criteria.