National Cancer Database study of clinicopathologic features and outcomes of neuroendocrine neoplasms of the breast

Neuroendocrine neoplasms (NENs) of the breast are subcategorized as well-differentiated neuroendocrine tumor (NET) and poorly differentiated neuroendocrine carcinoma (NEC). Analysis of the National Cancer Database (2004-2015) found that after adjusting for known prognostic factors, both NET (HR 1.41; p=0.005) and NEC (HR 2.11; p<0.001) of the breast had significantly worse overall survival compared with invasive adenocarcinoma, not otherwise specified, of the breast. Both NET and NEC benefited from endocrine therapy if the tumors were HR-positive. NEC, but not NET, also benefited from chemotherapy.