{"entity":{"id":"secretory-carcinoma-breast","kind":"cancer","name":"Secretory carcinoma of the breast","aka":["Juvenile carcinoma of the breast","Secretory breast carcinoma","SBC","ETV6-NTRK3 fusion-positive breast carcinoma"],"tldr":"Secretory carcinoma is a very rare, slow-growing breast cancer first described in children, whose cells make milk-like secretions. It is usually triple-negative but almost always carries the ETV6-NTRK3 gene fusion, so the rare patient whose tumour spreads can be treated with an NTRK inhibitor tablet, and most need no chemotherapy.","summary":"Secretory breast carcinoma is a rare subtype of infiltrating ductal-origin carcinoma that expresses the ETV6-NTRK3 gene fusion, first cloned in paediatric mesenchymal cancers; the fusion was confirmed in 12 of 13 cases (92 percent) but in no other ductal carcinomas, and its expression transformed mammary epithelial cells into gland-forming tumours in mice, establishing it as a primary oncogenic event (Tognon 2002). Histologically the tumour shows microcystic, solid and tubular patterns with abundant intracellular and extracellular secretion, is usually low grade and often triple-negative or weakly ER-positive with a basal-like immunophenotype (Cserni 2021; Thomas 2023). The European Working Group for Breast Screening Pathology places secretory carcinoma among the triple-negative special types with an indolent course whose patients are unlikely to benefit from systemic chemotherapy, favouring surgery with or without radiotherapy (Cserni 2021). Because the ETV6-NTRK3 fusion is an NTRK fusion, the tumour-agnostic approvals of larotrectinib and entrectinib apply to the rare metastatic case.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Secretory_carcinoma","links":[{"label":"Tognon, Cancer Cell 2002: the ETV6-NTRK3 gene fusion as a primary event in secretory breast carcinoma","url":"https://doi.org/10.1016/s1535-6108(02)00180-0"},{"label":"Cserni, Cancers 2021: triple-negative breast cancer histological subtypes with a favourable prognosis (European Working Group for Breast Screening Pathology)","url":"https://doi.org/10.3390/cancers13225694"},{"label":"Thomas, NPJ Breast Cancer 2023: rare subtypes of triple-negative breast cancer","url":"https://doi.org/10.1038/s41523-023-00554-x"}],"tags":["breast","tnbc","subtype-page"],"related":["tnbc","adenoid-cystic-carcinoma-breast"],"cancers":[],"sections":[],"technologies":[],"targets":[],"drugs":["larotrectinib","entrectinib"],"companies":[],"institutions":[],"pathways":[],"terms":["tumour-agnostic","tumour-grade"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"breast","burden":"Very rare (under 0.15 percent of breast cancers in most series; the review literature counts it among the 5 to 10 percent of triple-negative cancers that are rare subtypes); it can occur in children and young adults as well as adults (Thomas 2023).","subtypes":["Secretory carcinoma arising in children and adolescents (juvenile carcinoma)","Adult secretory carcinoma (the majority of cases)","Invasive carcinoma of no special type (ductal) with secretory features"],"biomarkers":["ETV6-NTRK3 fusion (about 92 percent) and pan-TRK immunohistochemistry","Triple-negative or low ER status with low grade","S100 and mammaglobin expression"],"standardOfCare":[{"setting":"Localised disease","approach":"Surgery with clear margins, radiotherapy after breast conservation; chemotherapy is usually not indicated for this indolent type (European working group consensus).","refs":["lumpectomy","mastectomy","sentinel-node"]},{"setting":"Metastatic disease (rare)","approach":"NTRK inhibitors (larotrectinib, entrectinib) under their tumour-agnostic approvals for NTRK fusion-positive solid tumours.","refs":["larotrectinib","entrectinib","tumour-agnostic"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"tnbc"},"route":"/cancers/secretory-carcinoma-breast/","neighbours":{"cancer":[{"id":"acinic-cell-carcinoma-salivary","kind":"cancer","name":"Acinic cell carcinoma of the salivary glands","route":"/cancers/acinic-cell-carcinoma-salivary/"},{"id":"adenoid-cystic-carcinoma-breast","kind":"cancer","name":"Adenoid cystic carcinoma of the breast","route":"/cancers/adenoid-cystic-carcinoma-breast/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"drug":[{"id":"entrectinib","kind":"drug","name":"Entrectinib","route":"/drugs/entrectinib/"},{"id":"larotrectinib","kind":"drug","name":"Larotrectinib","route":"/drugs/larotrectinib/"}],"term":[{"id":"tumour-grade","kind":"term","name":"Grade","route":"/terms/tumour-grade/"},{"id":"lumpectomy","kind":"term","name":"Lumpectomy (breast-conserving surgery)","route":"/terms/lumpectomy/"},{"id":"mastectomy","kind":"term","name":"Mastectomy","route":"/terms/mastectomy/"},{"id":"tumour-agnostic","kind":"term","name":"Tumour-agnostic (tissue-agnostic) approval","route":"/terms/tumour-agnostic/"}],"technology":[{"id":"sentinel-node","kind":"technology","name":"Sentinel lymph node biopsy","route":"/technologies/sentinel-node/"}]}}