Effective role of hormonal therapy in metastatic primary neuroendocrine breast carcinoma.

Primary neuroendocrine carcinoma (PNEC) of the breast is extremely rare.(1) Because of the rarity of this cancer, long-term prognosis, biologic behavior, and treatment are not well known. PNEC can have high expression of estrogen receptor (ER) and progesterone receptor (PR). It is important to differentiate PNEC of the breast from other metastatic diseases to the breast because of the differences in treatment. We herein report the successful treatment of a patient with PNEC of the breast and high expression of ER and PR by means of hormonal therapy.