{"entity":{"id":"neuroendocrine-neoplasms-breast","kind":"cancer","name":"Neuroendocrine neoplasms of the breast","aka":["Neuroendocrine carcinoma of the breast","Neuroendocrine tumour of the breast","Primary small cell neuroendocrine carcinoma of the breast","Breast carcinoma with neuroendocrine differentiation"],"tldr":"Neuroendocrine neoplasms of the breast are rare breast cancers whose cells make hormone-like granules, ranging from slow-growing tumours to small cell carcinoma like that of the lung. They are easily mistaken for ordinary breast cancer or for spread from elsewhere; slow-growing forms are treated like hormone-driven breast cancer and small cell forms with the lung small cell regimens.","summary":"The 2019 WHO classification divides neuroendocrine neoplasms of the breast into well-differentiated neuroendocrine tumour, neuroendocrine carcinoma (small cell and large cell) and, separately, invasive carcinomas of other types with neuroendocrine differentiation such as solid papillary and hypercellular mucinous carcinoma (Tan 2020). The entity as first defined by the WHO in 2012 spans well-differentiated tumours to highly aggressive small cell carcinomas; correct diagnosis needs an interdisciplinary approach because the tumours are misclassified as carcinoma with neuroendocrine differentiation, no special type carcinoma or a metastasis to the breast, and in one specialised unit only five of 612 neuroendocrine patients had a breast primary (Cancers 2020). Primary small cell neuroendocrine carcinoma of the breast is histologically indistinguishable from the lung tumour, so a primary elsewhere must be excluded, and there is no standard approach to treatment because only a limited number of cases have been reported (Int J Surg Case Rep 2017).\n\nHow it differs from its parent: the well-differentiated tumours are usually hormone-receptor positive and behave like luminal breast cancer, whereas the small cell carcinomas are treated with the platinum-etoposide regimens of small cell lung cancer rather than the breast pathways; neither has a trial of its own.\n\nHow common: no incidence figure is given in the sources read.\n\nTreatment: well-differentiated tumours as HR-positive breast cancer on the parent page; small cell and large cell neuroendocrine carcinoma with surgery and the extrapulmonary neuroendocrine carcinoma pathway (platinum and etoposide, radiotherapy), as the case literature describes (Int J Surg Case Rep 2017).","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Breast_cancer_classification","links":[{"label":"Tan 2020, Histopathology: the 2019 WHO classification of tumours of the breast","url":"https://doi.org/10.1111/his.14091"},{"label":"Cancers 2020: primary neuroendocrine neoplasms of the breast, case series and literature review","url":"https://doi.org/10.3390/cancers12030733"},{"label":"Int J Surg Case Rep 2017: primary small cell neuroendocrine carcinoma of the breast, case and review","url":"https://doi.org/10.1016/j.ijscr.2017.07.002"}],"tags":["subtype-page","wave4","breast"],"related":["breast-cancer","breast-hr-positive","extrapulmonary-nec","papillary-carcinoma-breast","mucinous-carcinoma-breast"],"cancers":[],"sections":[],"technologies":["endocrine-therapy"],"targets":[],"drugs":["cisplatin","etoposide"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"breast","burden":"Rare and probably under-diagnosed: five patients among 612 seen over 2008 to 2019 in one specialised neuroendocrine unit (Cancers 2020). No population figure is given in the sources read.","subtypes":["Well-differentiated neuroendocrine tumour of the breast (luminal, HR-positive)","Small cell neuroendocrine carcinoma of the breast","Large cell neuroendocrine carcinoma of the breast","Invasive carcinoma with neuroendocrine differentiation (solid papillary, hypercellular mucinous)"],"biomarkers":["Synaptophysin, chromogranin A and INSM1","Ki-67 and grade","Oestrogen and progesterone receptor (positive in well-differentiated tumours)","Exclusion of a lung or gut primary by imaging"],"standardOfCare":[{"setting":"Well-differentiated tumour","approach":"Treated as HR-positive breast cancer.","refs":["breast-hr-positive","endocrine-therapy"]},{"setting":"Small cell or large cell neuroendocrine carcinoma","approach":"Surgery and the extrapulmonary neuroendocrine carcinoma pathway (platinum and etoposide, radiotherapy); no standard exists.","refs":["extrapulmonary-nec","cisplatin","etoposide"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"breast-cancer"},"route":"/cancers/neuroendocrine-neoplasms-breast/","neighbours":{"cancer":[{"id":"breast-cancer","kind":"cancer","name":"Breast cancer (all types)","route":"/cancers/breast-cancer/"},{"id":"extrapulmonary-nec","kind":"cancer","name":"Extrapulmonary neuroendocrine carcinoma","route":"/cancers/extrapulmonary-nec/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"invasive-lobular-carcinoma","kind":"cancer","name":"Invasive lobular carcinoma of the breast","route":"/cancers/invasive-lobular-carcinoma/"},{"id":"mucinous-carcinoma-breast","kind":"cancer","name":"Mucinous carcinoma of the breast","route":"/cancers/mucinous-carcinoma-breast/"},{"id":"papillary-carcinoma-breast","kind":"cancer","name":"Papillary carcinomas of the breast (encapsulated, solid and invasive papillary)","route":"/cancers/papillary-carcinoma-breast/"}],"technology":[{"id":"endocrine-therapy","kind":"technology","name":"Endocrine therapy (SERMs, AIs, SERDs)","route":"/technologies/endocrine-therapy/"}],"drug":[{"id":"cisplatin","kind":"drug","name":"Cisplatin","route":"/drugs/cisplatin/"},{"id":"etoposide","kind":"drug","name":"Etoposide","route":"/drugs/etoposide/"}]}}