Predictors for axillary lymph node metastasis in primary neuroendocrine carcinomas of the breast and neuroendocrine differentiated breast cancers

Abstract

Aims: Primary neuroendocrine carcinomas of the breast (NEC) and neuroendocrine differentiated breast cancers are rare entities. The aim of this study was to investigate clinical and histopathological findings and predictors for axillary lymph node metastasis (ALNM) in primary neuroendocrine carcinomas of the breast (NEC) and neuroendocrine differentiated breast cancers (NEBC). Methods: Patients with a diagnosis of breast cancer with histopathological neuroendocrine features between the years 2015 and 2022 were retrospectively screened. The patients were divided into two main groups, the NEC and NEBC groups. The two groups were evaluated in terms of their clinical and histopathological characteristics and predictive factors for axillary lymph node. Results: A total of 35 patients [NEBC group: 24 patients, NEC group: 11 patients) were evaluated. At the time of diagnosis, the median age was 57 (NEC: 49 years, NEBC: 57.5). Of the 35 patients, 15 (57.1%) had ALNM, and lymphovascular invasion was detected in 16 (45.7%). When the whole patient population was evaluated for ALNM, it was found that lymphovascular invasion had an effect on ALNM (p=0.005). In the NEBC group, the rate of ALNM was associated with an increase in tumor diameter (p=0.035). Additionally, the tumor diameter was found to be predictive of ALNM in the ROC analysis (AUC: 0.753, 95% CI: 0.557-0.950, cut-off: 2.35 cm, p=0.035). Analyses of correlation revealed a low-level correlation between age and Ki-67 in the study cohort ( ρ= -0.341, p=0.45). Conclusion: NECs and NEBCs of the breast are uncommon tumors with a high ALNM potential. Patients with lymphovascular invasion and a large tumor diameter should be carefully evaluated for ALNM. Further research is required to determine the most appropriate treatment strategy for these rare subtypes of breast cancers.