{"entity":{"id":"mucinous-carcinoma-breast","kind":"cancer","name":"Mucinous carcinoma of the breast","aka":["Mucinous carcinoma of the breast","Colloid carcinoma of the breast","Mucinous breast cancer","Pure mucinous carcinoma"],"tldr":"Mucinous carcinoma is a rare type of breast cancer in which the cancer cells float in pools of mucus they have made. It is usually hormone-receptor positive, slow-growing and less likely to reach the lymph nodes than ordinary breast cancer, so its outlook is good and it is treated like other hormone-driven breast cancer.","summary":"The WHO classification defines pure mucinous carcinoma by clusters of low-grade cells in lakes of extracellular mucin making up over 90 percent of the tumour, and separates it from mixed mucinous carcinoma and from mucinous cystadenocarcinoma (Tan 2020). In a Taiwanese series of 93 pure mucinous carcinomas compared with 2,674 infiltrating ductal carcinomas, hormone receptor expression was higher and grade, hormone receptor status and node involvement were all more favourable, confirming its less aggressive behaviour (World J Surg Oncol 2013).\n\nHow it differs from its parent: mucin makes the tumour soft and well-circumscribed, so it can look benign on imaging; nodal spread is uncommon in the pure form; and the mixed form (mucinous with ordinary no special type carcinoma) behaves like the ordinary component and is treated as such.\n\nHow common: about 3.5 percent of breast cancers in the Taiwanese series (World J Surg Oncol 2013).\n\nTreatment: as HR-positive breast cancer, following the parent page, with endocrine therapy and usually no chemotherapy for the pure form; the sources read report treatment patterns, not trials in this type.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Mucinous_carcinoma","links":[{"label":"Tan 2020, Histopathology: the 2019 WHO classification of tumours of the breast","url":"https://doi.org/10.1111/his.14091"},{"label":"World J Surg Oncol 2013: pure mucinous carcinoma of the breast, 93 cases against 2,674 ductal carcinomas","url":"https://doi.org/10.1186/1477-7819-11-139"},{"label":"Cancer Research UK: types of breast cancer","url":"https://www.cancerresearchuk.org/about-cancer/breast-cancer/types"}],"tags":["subtype-page","wave4","breast"],"related":["breast-cancer","breast-hr-positive","tubular-carcinoma-breast","papillary-carcinoma-breast","invasive-micropapillary-carcinoma-breast"],"cancers":[],"sections":[],"technologies":["endocrine-therapy"],"targets":[],"drugs":["tamoxifen","letrozole"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"breast","burden":"About 3.5 percent of newly diagnosed breast cancers in Taiwan (World J Surg Oncol 2013); typically a cancer of older women. No UK figure was found in the sources read.","subtypes":["Pure mucinous carcinoma (over 90 percent mucinous; luminal A)","Mixed mucinous carcinoma (treated as its no special type component)","Mucinous carcinoma with neuroendocrine differentiation (hypercellular type B)","Mucinous cystadenocarcinoma (very rare)"],"biomarkers":["Proportion of mucinous component (over 90 percent for pure)","Oestrogen and progesterone receptor (usually positive), HER2 (usually negative)","Node status"],"standardOfCare":[{"setting":"All stages","approach":"Treated as HR-positive breast cancer: surgery, radiotherapy after breast conservation, endocrine therapy; chemotherapy for the mixed form as for no special type disease.","refs":["breast-hr-positive","endocrine-therapy","tamoxifen","letrozole"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"breast-cancer"},"route":"/cancers/mucinous-carcinoma-breast/","neighbours":{"cancer":[{"id":"breast-cancer","kind":"cancer","name":"Breast cancer (all types)","route":"/cancers/breast-cancer/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"invasive-micropapillary-carcinoma-breast","kind":"cancer","name":"Invasive micropapillary carcinoma of the breast","route":"/cancers/invasive-micropapillary-carcinoma-breast/"},{"id":"neuroendocrine-neoplasms-breast","kind":"cancer","name":"Neuroendocrine neoplasms of the breast","route":"/cancers/neuroendocrine-neoplasms-breast/"},{"id":"papillary-carcinoma-breast","kind":"cancer","name":"Papillary carcinomas of the breast (encapsulated, solid and invasive papillary)","route":"/cancers/papillary-carcinoma-breast/"},{"id":"tubular-carcinoma-breast","kind":"cancer","name":"Tubular carcinoma of the breast","route":"/cancers/tubular-carcinoma-breast/"}],"technology":[{"id":"endocrine-therapy","kind":"technology","name":"Endocrine therapy (SERMs, AIs, SERDs)","route":"/technologies/endocrine-therapy/"}],"drug":[{"id":"letrozole","kind":"drug","name":"Letrozole (and other aromatase inhibitors)","route":"/drugs/letrozole/"},{"id":"tamoxifen","kind":"drug","name":"Tamoxifen","route":"/drugs/tamoxifen/"}]}}