# Appendiceal adenocarcinoma (mucinous and non-mucinous, including signet ring cell)

Source: https://onco.cc/cancers/appendiceal-adenocarcinoma/  
OnCo record `appendiceal-adenocarcinoma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

Because 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.

## Fields

- Kind: Cancer
- Last checked: 2026-09-18
- Also known as: Appendix adenocarcinoma; Colonic-type appendiceal adenocarcinoma; Mucinous appendiceal adenocarcinoma; Signet ring cell carcinoma of the appendix; High-grade appendiceal cancer
- Tags: subtype-page; gastrointestinal
- 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

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/appendiceal-adenocarcinoma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/appendiceal-adenocarcinoma/#overview [3 state-of-the-art points]
- Types and stages (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/appendiceal-adenocarcinoma/#what-it-is [6 subtypes]
- Symptoms and diagnosis (on the hub): How this cancer shows itself, how the diagnosis is confirmed, and the biomarkers clinicians test for. https://onco.cc/cancers/appendiceal-adenocarcinoma/#finding-it [6 biomarkers]
- Treatment (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/appendiceal-adenocarcinoma/#treating-it [4 settings, 4 decisions with options]
- Trials and papers (on the hub): Trials recruiting now, the landmark trials, the trials held by this cancer's subtypes, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/appendiceal-adenocarcinoma/#evidence [3 key papers, 5 milestones]
- Biology and targets (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/appendiceal-adenocarcinoma/#science [4 targets]
- Countries and centres (own page): Cases by country, the UK and NHS pathway and other country lenses, the expert centres with trials on record, and the centres named on this cancer's subtypes. https://onco.cc/cancers/appendiceal-adenocarcinoma/where-you-are/
- Decisions and support (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/appendiceal-adenocarcinoma/#living-with-it [17 questions, 6 red cards]
- Pipeline and open problems (own page): Everything in development, the medicines held by this cancer's subtypes, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/appendiceal-adenocarcinoma/coming/ [6 medicines, 4 open problems]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/appendiceal-adenocarcinoma/data/ [36 connected records]

## Standard of care

- Localised disease: Right hemicolectomy with lymphadenectomy; adjuvant FOLFOX or CAPOX for node-positive or high-risk stage II disease, extrapolated from colon cancer. ([Colectomy](https://onco.cc/terms/colectomy/), [Lymphadenectomy (lymph node dissection)](https://onco.cc/terms/lymphadenectomy/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/))
- Peritoneal metastases, resectable: Cytoreductive surgery with HIPEC (mitomycin or oxaliplatin) in fit patients with limited disease and favourable histology, with perioperative systemic chemotherapy. ([HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/), [HIPEC (hyperthermic intraperitoneal chemotherapy)](https://onco.cc/terms/hipec-procedure/), [Mitomycin C](https://onco.cc/drugs/mitomycin/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [Peritoneal metastasis](https://onco.cc/terms/peritoneal-metastasis/))
- Unresectable or distant metastatic disease: FOLFOX or CAPOX with or without bevacizumab; FOLFIRI in second line; pembrolizumab for mismatch-repair-deficient tumours. ([FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [FOLFIRI (5-FU, leucovorin, irinotecan)](https://onco.cc/drugs/folfiri/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/))
- Signet ring cell carcinoma with extensive peritoneal disease: Systemic chemotherapy first; cytoreduction only for exceptional responders. ([FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/))

## State of the art

- 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.

## Open problems

- 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.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Appendix_cancer
- NCCN Colon Cancer (appendiceal adenocarcinoma): https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428
- Wikipedia: https://en.wikipedia.org/wiki/Appendix_cancer

## Connected records

- cancers: [Appendiceal cancer and pseudomyxoma peritonei](https://onco.cc/cancers/appendiceal/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Goblet cell adenocarcinoma of the appendix](https://onco.cc/cancers/goblet-cell-adenocarcinoma/), [Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei](https://onco.cc/cancers/low-grade-appendiceal-mucinous-neoplasm/), [Mucinous adenocarcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-mucinous-adenocarcinoma/), [Signet ring cell carcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-signet-ring-cell-carcinoma/)
- technologies: [CT (computed tomography)](https://onco.cc/technologies/ct/), [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/), [MRI](https://onco.cc/technologies/mri/)
- targets: [KRAS](https://onco.cc/targets/kras/), [TP53](https://onco.cc/targets/tp53/)
- drugs: [Bevacizumab](https://onco.cc/drugs/bevacizumab/), [CAPOX (capecitabine, oxaliplatin)](https://onco.cc/drugs/capox/), [FOLFIRI (5-FU, leucovorin, irinotecan)](https://onco.cc/drugs/folfiri/), [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [Mitomycin C](https://onco.cc/drugs/mitomycin/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- terms: [Colectomy](https://onco.cc/terms/colectomy/), [Cytoreductive surgery](https://onco.cc/terms/cytoreductive-surgery/), [HIPEC (hyperthermic intraperitoneal chemotherapy)](https://onco.cc/terms/hipec-procedure/), [Lymphadenectomy (lymph node dissection)](https://onco.cc/terms/lymphadenectomy/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/), [Peritoneal cancer index](https://onco.cc/terms/peritoneal-carcinomatosis-index/), [Peritoneal metastases from bowel cancer](https://onco.cc/terms/colorectal-peritoneal-metastases/), [Peritoneal metastasis](https://onco.cc/terms/peritoneal-metastasis/)
- key papers: [PSOGI consensus for classification and pathological reporting of pseudomyxoma peritonei and associated appendiceal neoplasia](https://onco.cc/key-papers/paper-psogi-pseudomyxoma-appendiceal-classification-am-j-surg-pathol-2016/), [The 2019 WHO classification of tumours of the digestive system](https://onco.cc/key-papers/paper-who-2019-digestive-system-tumours-nagtegaal-histopathology-2020/), [The Chicago Consensus on peritoneal surface malignancies: management of appendiceal neoplasms](https://onco.cc/key-papers/paper-chicago-consensus-appendiceal-neoplasms-cancer-2020/)

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JSON: https://onco.cc/api/v1/entities/appendiceal-adenocarcinoma.json