HER-2 positive primary solid neuroendocrine carcinoma of the breast: a case report and review of the literature

CDK4/6 and aromatase inhibitors as first-line treatment in metastatic high-grade neuroendocrine carcinoma of the breast: A case report

Key Clinical Message

There is no consensus regarding the therapeutic approach of breast neuroendocrine carcinomas (NECs). As most NECs are hormone receptor positive and HER-2 negative, we suggest that endocrine-based strategies may play a leading role. Here, we report a new treatment strategy by incorporating CDK4/6 inhibitors in the therapeutic armamentarium.

Abstract

Primary neuroendocrine neoplasms of the breast constitute a rare entity. They are characterized by predominant neuroendocrine differentiation and are further divided into well-differentiated neuroendocrine tumors and poorly differentiated (high-grade) neuroendocrine carcinomas (NECs). Regarding their therapeutic approach, there are no standardized guidelines. Herein, we present the first case ever reported, concerning a female patient with de novo metastatic breast NEC who received hormonal therapy, a combination of a CDK4/6 inhibitor palbociclib with letrozole and triptorelin, as first-line treatment with significant clinical and radiological response. As most NECs are estrogen receptor and/or progesterone receptor positive and HER-2 negative, we suggest that hormonal therapy may play a leading role even in the first-line setting. The present report provides a new treatment strategy by incorporating CDK4/6 inhibitors in the therapeutic armamentarium of breast NECs.

Head to head: Do neuroendocrine tumours in the breast truly exist?

Breast cancer (BC) is a heterogeneous disease with a spectrum of morphological features. Concepts of histogenesis and differentiation in BC remain controversial. Recent evidence supports differentiation rather than histogenesis as the underlying mechanism for the myriad morphological appearances of BC. Prognosis and response to therapy are determined by a combination of factors including tumour grade, stage and receptor status whereas tumour histological types play an independent role in only limited examples. Neuroendocrine tumours (NETs) comprise one of the most debated entities in the breast since their first description. Apart from the rare small cell NE carcinoma (NEC) which has well-characterised features similar to their counterparts in other organs, the true existence, diagnostic criteria and clinical significance of NE neoplasms (NENs) in the breast are shrouded in controversy. At the core of this discussion is whether normal NE cells exist in the breast, and if breast NETs have distinct morphology and clinical behaviour. When NETs are encountered in the breast, metastatic origin has to be excluded. The more frequent situation in which NE differentiation is observed in breast cancers is in the context of recognisable, morphologically well described special type neoplasms like the hypercellular mucinous carcinoma and solid papillary carcinoma. In this review, arguments for and against maintaining the category of NENs in the breast are articulated in relation to existing literature on this group of unusual tumours.

Rare Human Epidermal Growth Factor Receptor 2 (HER-2)-Positive Neuroendocrine Carcinoma of the Breast: A Case Report with 9-Year Follow-up

BACKGROUND Neuroendocrine carcinoma of the breast (NECB) is very rare, accounting for 0.1% of all breast tumors and less than 1% of all neuroendocrine tumors. Most NECBs are hormone receptor-positive and human epidermal growth factor receptor 2 (HER-2)-negative and more than 50% are the luminal B subtype. Because prospective studies of NECB are lacking, treatment is the same as for other breast tumors. CASE REPORT A 70-year-old woman was diagnosed with NECB in February 2011. She underwent radical right mastectomy and right axillary node dissection. Final histopathological examination revealed NECB with positive axillary nodes (N1). The tumor cells were 100% positive for estrogen receptors and 10% positive for progesterone receptors. The HER-2 status was 3+. According to the Tumor, Node, Metastasis (TNM) Classification of Malignant Tumors, the pathologic stage was IIB - pT2pN1cM0. The histologic grade was 2 and the Ki-67 proliferation index was 5.7%. The patient received adjuvant chemotherapy, radiation therapy, IV trastuzumab, and endocrine therapy. After 9 years of follow-up, she remains disease-free. CONCLUSIONS As far as we know, this is only the second report describing treatment of HER-2-positive NECB with trastuzumab. A literature review shows that it is the first report of treatment of HER-2-positive primary NECB with adjuvant trastuzumab. In similar cases, long-term follow-up is recommended because of the potential for multiple metastases of NECB even years after completion of adjuvant therapy.

Neuroendocrine breast carcinoma: a rare but challenging entity

Breast carcinoma with neuroendocrine differentiation, also known as neuroendocrine breast carcinoma (NEBC), includes a heterogeneous group of rare tumors, which account for 2–5% of all invasive breast carcinomas. Because of their low incidence, most of the current limited knowledge of these tumors derives from anecdotal case reports or small retrospective series. The diagnosis of NEBC is based on the presence of morphological features similar to gastrointestinal and lung NETs and neuroendocrine markers. NEBCs are usually hormone receptors positive and HER2 negative, but despite this luminal phenotype, most recent studies suggested that NEBC could be associated with worse prognosis compared to invasive breast cancer without neuroendocrine differentiation. Due to its rarity and lack of randomized data, there is little evidence to guide the choice of treatment, so NEBC is currently treated as any invasive breast carcinoma not-otherwise specified. Recently, attempts to molecularly characterize NEBC have been made, in order to provide new targets for a more personalized treatment of this uncommon entity.

Dramatic response to cyclin D-dependent kinase 4/6 inhibitor in refractory poorly differentiated neuroendocrine carcinoma of the breast

Neuroendocrine tumors are a rare subset of breast carcinomas. Commonly, platinum-based doublet is used as a systemic treatment option for high-grade neuroendocrine carcinomas from lung, gastrointestinal, and genitourinary origins. In comparison to other breast cancers, neuroendocrine carcinomas have unique genomic features and different treatment strategies. We present a patient with high-grade neuroendocrine carcinoma of the breast who had a successful and durable response to the cyclin D-dependent kinase (CDK) 4/6 inhibitor palbociclib in conjunction with endocrine therapy. This patient was refractory to commonly used platinum-based chemotherapy as well as hormone-based treatment. To date, this is the first published case of use of CDK 4/6 inhibitor in primary neuroendocrine carcinoma of the breast.

Primary neuroendocrine tumour of the breast: a case report and review of the literature

Primary neuroendocrine tumour of the breast is a rare entity that first appeared in the 2003 World Health Organisation (WHO) classification of breast tumours. The data currently available on its prognosis are contradictory, although it seems clear that histological varieties such as small cell neuroendocrine carcinoma have a worse prognosis, due to their low degree of differentiation. The treatment of choice is surgery, and the indications for chemotherapy or radiotherapy do not differ greatly from those used for other breast tumours. It is crucial to underline the difficulty of establishing treatment protocols due to the low incidence of this histological type.