Abstract
BACKGROUND: Primary neuroendocrine breast carcinomas (NEBCs) are an extremely rare and underrecognized subtype of mammalian carcinoma. The prognostic factors for NEBCs remain controversial. METHODS: In this multicenter retrospective study, the prognostic factors for patients with primary NEBCs who underwent surgery and had a pathologically confirmed diagnosis of neuroendocrine carcinoma in China and the United States were examined. The endpoints were disease-free survival (DFS) and overall survival (OS). RESULTS: A total of 51 Chinese patients and 98 US patients were included. In the Chinese cohort, tumor grade and Ki-67 levels were prognostic factors for DFS in univariate analysis (hazard ratio [HR] = 5.11 [1.67-15.60], p = 0.004; HR = 57.70 [6.36-523.40], p < 0.001, respectively) and multivariate analysis (HR = 100.52 [1.33-7570.21], p = 0.037; HR = 31.47 [1.05-945.82], p = 0.047, respectively). In the US cohort, age was an important prognostic factor for OS in univariate analysis (HR = 1.09 [1.04-1.15], p = 0.001). The random effects model for the combined cohorts revealed age and positive expression of estrogen receptor (ER) as potential prognostic factors for OS (HR = 1.08 [1.01-1.14], p = 0.015; HR = 0.10 [0.02-0.44], p = 0.003, respectively). CONCLUSIONS: Tumor grade and Ki-67 levels are important prognostic factors for DFS of patients with primary NEBCs. Age and ER status are important prognostic factors for OS of patients with primary NEBCs.