[178] Neuroendocrine Carcinoma (NEC) of the Breast – Clinicopathological Study of 90 NEC Cases in Conjunction with 1505 Non-NEC Cases

Tomonori Kawasaki, Kunio Mochizuki, Tetsuo Kondo, Hideko Yamauchi, Shingo Inoue, Masayuki Inoue, Naoki Oishi, Tetsu Yamane, Tadao Nakazawa, Dongfeng Niu, Hiroshi Yagata, Hiroko Tsunoda, Hiroshi Onishi, Hideki Fujii, Ryohei Katoh. University of Yamanashi, Yamanashi, Japan; St. Luke's International Hospital, Tokyo, Japan

Background: The World Health Organization (WHO) classifies mammary neuroendocrine carcinoma (NEC), defined as >50% neoplastic cells expressing specific NE markers (i.e. chromogranin A and/or synaptophysin), as a special tumor entity representing only about 2-5% of breast cancers. However, its biological behavior and prognosis are still controversial.
Design: To clarify clinical significance and biological characteristics, 90 NECs of the breast were investigated and the clinicopathological findings compared with those of 1505 non-NECs.
Results: NECs accounted for 5.6% of all breast carcinomas in our study, and the mean patient age was 53.9 years. Pathological features of NECs included low nuclear grade (71%), earlier disease stage, absence of lymphatic permeation (70%), absence of coagulation necrosis (76%), absence of calcification (51%), weak inflammatory reaction (82%), estrogen receptor positivity (97%), progesterone receptor positivity (88%) and low HER2 score (P<0.05). The characteristic histological architecture of NECs was a predominantly solid growth of cancer cells (P<0.05) and a highly-vascular fibrovascular stroma. Cancer cells were polygonal or occasionally spindle-shaped with relatively well-developed, fine-granular cytoplasm and round to ovoid nuclei with fine and/or granular chromatin. Mucin production was occasionally seen. Ten cases (11%) had NEC recurrences and 6 (7%) died due to the tumor (mean 72 months post surgery). The recurrent NECs in these 10 cases were characterized pathologically by high nuclear grade (70%), pT2-4 (90%), axillary lymph node metastasis (80%) and lymphatic involvement (80%). Distant metastases of NECs usually affected the liver and bone (70%). The main cause of death was liver failure (83%) due to liver metastasis. Preoperative neoadjuvant chemotherapy was performed in six NEC cases; a mild therapeutic effect was obtained in five cases and no effect in one.
Conclusions: NECs of the breast had distinctive clinicopathological features, with most constituting a low-grade tumor group. However, recurrence and/or distant metastasis were more common in cases with high-grade breast NECs and this tumor group would, therefore, need more aggressive and/or novel therapeutic approaches.
Category: Breast

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 4, Tuesday Afternoon


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