{"entity":{"id":"colorectal-medullary-carcinoma","kind":"cancer","name":"Medullary carcinoma of the colon","aka":["Medullary carcinoma of the large intestine","Medullary colorectal carcinoma","Medullary adenocarcinoma of the colon"],"tldr":"Medullary carcinoma is a very rare form of bowel cancer in which sheets of poorly formed cells are packed with immune cells; almost all cases are mismatch-repair deficient and it occurs mostly in older women on the right side. Despite its ugly appearance it does at least as well as ordinary bowel cancer, and because of its immune features it is a natural candidate for immunotherapy.","summary":"The WHO classification lists medullary carcinoma as a distinct colorectal adenocarcinoma type with solid sheets of poorly differentiated cells, vesicular nuclei and a prominent intraepithelial lymphocytic infiltrate, nearly always mismatch-repair deficient (Nagtegaal 2020). In SEER it was extremely rare (5 to 8 per 10,000 colon cancers), most common in the proximal colon, twice as common in women who presented at a lower stage with a trend to favourable prognosis, and no case was reliably identified in the rectum or appendix (International Journal of Oncology 2010). Loss of MLH1 and PMS2 was found in more than 80 percent of 18 cases, most were negative for CK7, CK20 and CDX2, and cadherin-17 and SATB2 were expressed in 89 percent, which matters when it presents as a carcinoma of unknown primary (Archives of Pathology 2014). In 105 cases the microenvironment showed strong interferon-gamma-induced immunoregulatory gene expression, including IDO-1, distinct from other microsatellite-unstable carcinomas (Modern Pathology 2016).\n\nHow it differs from its parent: it is the extreme of the mismatch-repair deficient, right-sided, immune-rich colon cancer that the MSI-high page describes, with a distinctive marker profile (CDX2-negative) that can mislead the pathologist.\n\nHow common: 5 to 8 per 10,000 colon cancers (International Journal of Oncology 2010).\n\nTreatment: as the colorectal and MSI-high pages by stage, with checkpoint inhibitors for mismatch-repair deficient disease; there is no trial in the type.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Colorectal_cancer","links":[{"label":"Nagtegaal 2020, Histopathology: the 2019 WHO classification of tumours of the digestive system","url":"https://doi.org/10.1111/his.13975"},{"label":"International Journal of Oncology 2010: medullary carcinoma of the large intestine, SEER population analysis","url":"https://doi.org/10.3892/ijo_00000741"},{"label":"Archives of Pathology 2014: cadherin-17 and SATB2 in medullary carcinoma of the large intestine","url":"https://doi.org/10.5858/arpa.2013-0452-oa"},{"label":"Modern Pathology 2016: medullary carcinoma of the colon, immunoregulatory microenvironment in 105 cases","url":"https://doi.org/10.1038/modpathol.2016.54"}],"tags":["subtype-page","wave4","colorectal"],"related":["colorectal","msi-high-colorectal","colon-cancer","colorectal-mucinous-adenocarcinoma","cancer-of-unknown-primary"],"cancers":[],"sections":[],"technologies":[],"targets":[],"drugs":["pembrolizumab","nivolumab"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"gastrointestinal","burden":"About 5 to 8 cases for every 10,000 colon cancers, a mean annual incidence of 3.47 per 10 million population in SEER 1973 to 2006; mean age 69.3, twice as common in women, 74 percent in the proximal colon (International Journal of Oncology 2010).","subtypes":["Medullary carcinoma, mismatch-repair deficient (the usual form; right-sided, MSI-high)","Medullary carcinoma, mismatch-repair proficient (rare)"],"biomarkers":["MLH1 and PMS2 loss (over 80 percent)","Cadherin-17 and SATB2 positive; CK7, CK20 and CDX2 usually negative","Tumour-infiltrating lymphocytes and IDO-1 expression","BRAF V600E (sporadic MSI-high)"],"standardOfCare":[{"setting":"All stages","approach":"Treated as MSI-high colorectal cancer by stage, with checkpoint inhibitors for mismatch-repair deficient disease.","refs":["msi-high-colorectal","colorectal","pembrolizumab","nivolumab"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"colorectal"},"route":"/cancers/colorectal-medullary-carcinoma/","neighbours":{"cancer":[{"id":"cancer-of-unknown-primary","kind":"cancer","name":"Cancer of unknown primary (CUP)","route":"/cancers/cancer-of-unknown-primary/"},{"id":"colon-cancer","kind":"cancer","name":"Colon cancer (adenocarcinoma of the colon)","route":"/cancers/colon-cancer/"},{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"},{"id":"msi-high-colorectal","kind":"cancer","name":"Mismatch-repair deficient (MSI-high) colorectal cancer","route":"/cancers/msi-high-colorectal/"},{"id":"colorectal-mucinous-adenocarcinoma","kind":"cancer","name":"Mucinous adenocarcinoma of the colon and rectum","route":"/cancers/colorectal-mucinous-adenocarcinoma/"}],"drug":[{"id":"nivolumab","kind":"drug","name":"Nivolumab","route":"/drugs/nivolumab/"},{"id":"pembrolizumab","kind":"drug","name":"Pembrolizumab","route":"/drugs/pembrolizumab/"}]}}