{"entity":{"id":"appendiceal-adenocarcinoma","kind":"cancer","name":"Appendiceal adenocarcinoma (mucinous and non-mucinous, including signet ring cell)","aka":["Appendix adenocarcinoma","Colonic-type appendiceal adenocarcinoma","Mucinous appendiceal adenocarcinoma","Signet ring cell carcinoma of the appendix","High-grade appendiceal cancer"],"tldr":"Appendiceal adenocarcinoma is the invasive, gland-forming form of appendix cancer that behaves more like bowel cancer than the jelly-producing low-grade tumours, spreading to lymph nodes and the abdominal lining. It is treated with right hemicolectomy and bowel-cancer chemotherapy, and peritoneal spread with cytoreductive surgery and heated intraperitoneal chemotherapy in fit patients.","summary":"Appendiceal adenocarcinoma invades the wall of the appendix as a carcinoma and is subdivided into mucinous adenocarcinoma (more than half the tumour is extracellular mucin), non-mucinous or colonic-type adenocarcinoma, and signet ring cell carcinoma when half or more of the cells are signet ring cells. Most are found after appendicectomy for suspected appendicitis or at operation for peritoneal disease, and staging follows the colorectal TNM system. The genetics differ from colorectal cancer: KRAS and GNAS mutations are common, APC mutations rare, microsatellite instability uncommon, and TP53 and SMAD4 mutations mark high-grade tumours; a 2025 analysis of appendiceal cancers also found that many were diagnosed in people under 50, mirroring early-onset colorectal cancer.\n\nBecause the disease is rare, treatment is extrapolated from colon cancer. Right hemicolectomy with lymphadenectomy is recommended for all adenocarcinomas, and adjuvant FOLFOX or CAPOX for node-positive or high-risk disease, without trial evidence specific to the appendix. Peritoneal metastases, the dominant pattern of spread, are treated with cytoreductive surgery and HIPEC in patients with a limited peritoneal cancer index and non-signet-ring histology, where series report median survival of several years, and with perioperative systemic chemotherapy; signet ring cell carcinoma with a high peritoneal cancer index does poorly even after cytoreduction. Unresectable or distant metastatic disease receives FOLFOX or CAPOX with or without bevacizumab, then FOLFIRI, and the rare mismatch-repair-deficient tumour is a candidate for pembrolizumab. Retrospective data suggest that non-mucinous tumours respond to chemotherapy like colorectal cancer while mucinous tumours respond less, and prospective trials in appendiceal cancer specifically are only now beginning.","asOf":"2026-09-18","wikipedia":"https://en.wikipedia.org/wiki/Appendix_cancer","links":[{"label":"NCCN Colon Cancer (appendiceal adenocarcinoma)","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428"},{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Appendix_cancer"}],"tags":["subtype-page","gastrointestinal"],"related":["low-grade-appendiceal-mucinous-neoplasm","goblet-cell-adenocarcinoma","appendiceal","colorectal"],"cancers":[],"sections":[],"technologies":["hipec","cytotoxic-chemotherapy","ct","mri","checkpoint-inhibitor"],"targets":["kras","tp53"],"drugs":["folfox","capox","folfiri","bevacizumab","mitomycin","pembrolizumab"],"companies":[],"institutions":[],"pathways":[],"terms":["hipec-procedure","peritoneal-metastasis","colectomy","lymphadenectomy","msi"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":["paper-chicago-consensus-appendiceal-neoplasms-cancer-2020","paper-who-2019-digestive-system-tumours-nagtegaal-histopathology-2020","paper-psogi-pseudomyxoma-appendiceal-classification-am-j-surg-pathol-2016"],"journals":[],"dependsOn":[],"notes":[],"group":"gastrointestinal","burden":"A minority of appendiceal tumours but the group that behaves like a true carcinoma, spreading to lymph nodes and the peritoneum; signet ring cell histology carries the worst outlook.","subtypes":["Mucinous appendiceal adenocarcinoma (extracellular mucin, GNAS and KRAS mutant)","Non-mucinous (colonic-type) appendiceal adenocarcinoma","Signet ring cell carcinoma of the appendix (worst prognosis)","Appendiceal adenocarcinoma with peritoneal metastases (cytoreduction and HIPEC in selected patients)","Node-positive appendiceal adenocarcinoma (right hemicolectomy and adjuvant chemotherapy)","Mismatch-repair-deficient appendiceal adenocarcinoma (rare; immunotherapy)"],"biomarkers":["Histological subtype and grade (mucinous, non-mucinous, signet ring)","TNM stage after right hemicolectomy","Peritoneal cancer index and completeness of cytoreduction","KRAS, GNAS, TP53 and SMAD4 mutations","Mismatch repair and microsatellite status (uncommon deficiency)","CEA, CA 19-9 and CA-125"],"standardOfCare":[{"setting":"Localised disease","approach":"Right hemicolectomy with lymphadenectomy; adjuvant FOLFOX or CAPOX for node-positive or high-risk stage II disease, extrapolated from colon cancer.","refs":["colectomy","lymphadenectomy","folfox","capox"],"guideline":{"version":"NCCN Guidelines: Colon Cancer (appendiceal section)","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428"}},{"setting":"Peritoneal metastases, resectable","approach":"Cytoreductive surgery with HIPEC (mitomycin or oxaliplatin) in fit patients with limited disease and favourable histology, with perioperative systemic chemotherapy.","refs":["hipec","hipec-procedure","mitomycin","folfox","capox","peritoneal-metastasis"],"guideline":{"version":"NCCN Guidelines: Colon Cancer (appendiceal section)","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428"}},{"setting":"Unresectable or distant metastatic disease","approach":"FOLFOX or CAPOX with or without bevacizumab; FOLFIRI in second line; pembrolizumab for mismatch-repair-deficient tumours.","refs":["folfox","capox","bevacizumab","folfiri","pembrolizumab","msi"],"guideline":{"version":"NCCN Guidelines: Colon Cancer (appendiceal section)","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428"}},{"setting":"Signet ring cell carcinoma with extensive peritoneal disease","approach":"Systemic chemotherapy first; cytoreduction only for exceptional responders.","refs":["folfox","capox","hipec"],"guideline":{"version":"NCCN Guidelines: Colon Cancer (appendiceal section)","url":"https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428"}}],"stateOfArt":["Right hemicolectomy and colorectal-style chemotherapy are the accepted standards, on extrapolated evidence.","Cytoreductive surgery with HIPEC extends survival in selected patients with peritoneal disease.","Molecular profiling shows appendiceal adenocarcinoma is not simply colon cancer of the appendix."],"history":[{"year":1998,"title":"Sugarbaker reports cytoreduction with intraperitoneal chemotherapy for appendiceal carcinomatosis","refs":["hipec"]},{"year":2010,"title":"WHO classification separates appendiceal mucinous neoplasms from adenocarcinoma","refs":[]},{"year":2016,"title":"PSOGI consensus defines mucinous adenocarcinoma and signet ring cell carcinoma grades","refs":[]},{"year":2019,"title":"Genomic studies show KRAS and GNAS mutations and few APC mutations, distinguishing appendiceal from colorectal cancer","refs":[]},{"year":2025,"title":"Analysis shows a large share of appendiceal cancers now arise in adults under 50","refs":[]}],"pipeline":["folfox","hipec","pembrolizumab"],"openProblems":["No adjuvant chemotherapy trial has ever been run in appendiceal adenocarcinoma.","Which patients with peritoneal disease benefit from HIPEC is defined only by retrospective series.","Signet ring cell carcinoma has no effective therapy.","Mucinous tumours respond poorly to standard chemotherapy and have no targeted option."],"parent":"appendiceal"},"route":"/cancers/appendiceal-adenocarcinoma/","neighbours":{"cancer":[{"id":"appendiceal","kind":"cancer","name":"Appendiceal cancer and pseudomyxoma peritonei","route":"/cancers/appendiceal/"},{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"},{"id":"goblet-cell-adenocarcinoma","kind":"cancer","name":"Goblet cell adenocarcinoma of the appendix","route":"/cancers/goblet-cell-adenocarcinoma/"},{"id":"low-grade-appendiceal-mucinous-neoplasm","kind":"cancer","name":"Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei","route":"/cancers/low-grade-appendiceal-mucinous-neoplasm/"}],"technology":[{"id":"ct","kind":"technology","name":"CT (computed tomography)","route":"/technologies/ct/"},{"id":"cytotoxic-chemotherapy","kind":"technology","name":"Cytotoxic chemotherapy","route":"/technologies/cytotoxic-chemotherapy/"},{"id":"hipec","kind":"technology","name":"HIPEC / PIPAC (intraperitoneal chemotherapy)","route":"/technologies/hipec/"},{"id":"checkpoint-inhibitor","kind":"technology","name":"Immune checkpoint inhibitors","route":"/technologies/checkpoint-inhibitor/"},{"id":"mri","kind":"technology","name":"MRI","route":"/technologies/mri/"}],"target":[{"id":"kras","kind":"target","name":"KRAS","route":"/targets/kras/"},{"id":"tp53","kind":"target","name":"TP53","route":"/targets/tp53/"}],"drug":[{"id":"bevacizumab","kind":"drug","name":"Bevacizumab","route":"/drugs/bevacizumab/"},{"id":"capox","kind":"drug","name":"CAPOX (capecitabine, oxaliplatin)","route":"/drugs/capox/"},{"id":"folfiri","kind":"drug","name":"FOLFIRI (5-FU, leucovorin, irinotecan)","route":"/drugs/folfiri/"},{"id":"folfox","kind":"drug","name":"FOLFOX (5-FU, leucovorin, oxaliplatin)","route":"/drugs/folfox/"},{"id":"mitomycin","kind":"drug","name":"Mitomycin C","route":"/drugs/mitomycin/"},{"id":"pembrolizumab","kind":"drug","name":"Pembrolizumab","route":"/drugs/pembrolizumab/"}],"term":[{"id":"colectomy","kind":"term","name":"Colectomy","route":"/terms/colectomy/"},{"id":"hipec-procedure","kind":"term","name":"HIPEC (hyperthermic intraperitoneal chemotherapy)","route":"/terms/hipec-procedure/"},{"id":"lymphadenectomy","kind":"term","name":"Lymphadenectomy (lymph node dissection)","route":"/terms/lymphadenectomy/"},{"id":"msi","kind":"term","name":"Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)","route":"/terms/msi/"},{"id":"peritoneal-metastasis","kind":"term","name":"Peritoneal metastasis","route":"/terms/peritoneal-metastasis/"}],"paper":[{"id":"paper-psogi-pseudomyxoma-appendiceal-classification-am-j-surg-pathol-2016","kind":"paper","name":"PSOGI consensus for classification and pathological reporting of pseudomyxoma peritonei and associated appendiceal neoplasia","route":"/key-papers/paper-psogi-pseudomyxoma-appendiceal-classification-am-j-surg-pathol-2016/"},{"id":"paper-who-2019-digestive-system-tumours-nagtegaal-histopathology-2020","kind":"paper","name":"The 2019 WHO classification of tumours of the digestive system","route":"/key-papers/paper-who-2019-digestive-system-tumours-nagtegaal-histopathology-2020/"},{"id":"paper-chicago-consensus-appendiceal-neoplasms-cancer-2020","kind":"paper","name":"The Chicago Consensus on peritoneal surface malignancies: management of appendiceal neoplasms","route":"/key-papers/paper-chicago-consensus-appendiceal-neoplasms-cancer-2020/"}]}}