Appendiceal cancer and pseudomyxoma peritonei
Rare tumours of the appendix that range from slow mucin-producing growths that fill the abdomen (pseudomyxoma peritonei) to aggressive adenocarcinomas. The slow forms are treated by extensive surgery with heated chemotherapy in the abdomen; the fast ones like colon cancer.
Appendiceal neoplasms include low-grade appendiceal mucinous neoplasms (LAMN) that rupture and seed the peritoneum as pseudomyxoma peritonei (PMP), mucinous and non-mucinous adenocarcinomas, goblet cell adenocarcinoma, and neuroendocrine tumours (the most common appendix tumour, usually cured by appendicectomy). PSOGI grading (acellular mucin, low-grade, high-grade, signet ring) predicts outcome. GNAS mutations mark low-grade mucinous disease; KRAS, TP53 and SMAD4 mark higher grade.
For PMP and peritoneal disease, cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC, usually mitomycin C) at an experienced centre gives 10-year survival of ~60-70% for low-grade disease (Sugarbaker, Chua 2012). Systemic chemotherapy (FOLFOX/CAPOX) is used for high-grade and unresectable disease but a randomised trial (2024) showed no benefit in low-grade mucinous carcinoma peritonei. Iterative CRS, mucolytics (bromelain-acetylcysteine) and intraperitoneal therapies are under study. Appendiceal adenocarcinoma is otherwise managed like colorectal cancer, with right hemicolectomy and stage-based chemotherapy.
State of the art today
- Grade, not stage, drives therapy: the 2024 randomised trial ended routine chemotherapy for low-grade mucinous carcinomatosis.
- Molecular profiling (GNAS vs KRAS/TP53) is beginning to formalise the low/high grade split.
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
- CRS-HIPEC turned PMP from a fatal disease into one with long survival for low-grade histology.
About 1-2 per 100,000 per year and rising, especially in adults under 50; most are found incidentally at appendicectomy.
Where the cases are
No country-level case numbers. This cancer is not mapped to a GLOBOCAN site.
Appendicectomy (LAMN without perforation) or right hemicolectomy (adenocarcinoma, goblet cell); adjuvant chemotherapy for node-positive adenocarcinoma by colorectal analogy.
Cytoreductive surgery with HIPEC at a peritoneal-surface-malignancy centre; repeat CRS for recurrence when feasible.
FOLFOX/CAPOX ± bevacizumab; systemic chemotherapy has no proven benefit in low-grade disease (randomised 2024).
Subtypes & biomarkers
top- LAMN / HAMN (low- and high-grade appendiceal mucinous neoplasm)
- Pseudomyxoma peritonei (low- vs high-grade, PSOGI)
- Mucinous and non-mucinous adenocarcinoma
- Goblet cell adenocarcinoma
- Signet ring cell carcinoma
- Appendiceal neuroendocrine tumour
- PSOGI histologic grade
- Peritoneal cancer index (PCI) and completeness of cytoreduction (CC score)
- GNAS (low-grade), KRAS, TP53, SMAD4
- CEA, CA19-9, CA-125
- MSI (rare)
Target prevalence in this cancer
- 1842Rokitansky describes a mucocele of the appendix
- 1884Werth coins 'pseudomyxoma peritonei'
- 1995Sugarbaker's peritonectomy procedures and HIPEC
- 2012Multi-institutional CRS-HIPEC outcomes: 10-year survival 63% (Chua, JCO)
- 2016PSOGI classification of appendiceal mucinous neoplasms and PMP
- 2024Randomised trial: no benefit of systemic chemotherapy in low-grade mucinous carcinoma peritonei
Open problems
- No effective systemic therapy for high-grade or signet-ring disease.
- Selection for CRS-HIPEC and management of recurrence after maximal surgery.
- Rising incidence in young adults is unexplained.
- Centralisation: outcomes depend heavily on centre experience.
Trials
topRecruiting now (live from ClinicalTrials.gov)
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Expert centres
topCentres linked to this cancer in OnCo
- via HIPEC / PIPAC (intraperitoneal chemotherapy)
- via HIPEC / PIPAC (intraperitoneal chemotherapy)
- European Society of Surgical OncologyBrussels, BEvia HIPEC / PIPAC (intraperitoneal chemotherapy)
- First Affiliated Hospital of Sun Yat-sen UniversityGuangzhou, CNvia HIPEC / PIPAC (intraperitoneal chemotherapy)
- Society of Surgical OncologyRosemont, IL, USvia HIPEC / PIPAC (intraperitoneal chemotherapy)
- UNICANCERParis, FRvia HIPEC / PIPAC (intraperitoneal chemotherapy)
Questions to ask
topQuestions to ask your oncologist about Appendiceal cancer and pseudomyxoma peritonei
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Why: Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example PSOGI histologic grade, Peritoneal cancer indexand completeness of cytoreduction, GNAS, KRAS, TP53, SMAD4, CEA, CA19-9, CA-125, MSI), and what were the results?Why: These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Why: Recognised subtypes for this cancer include LAMN / HAMN, Pseudomyxoma peritonei, Mucinous and non-mucinous adenocarcinoma.
- Is germline (inherited) genetic testing recommended for me or my family?Why: Inherited variants can change treatment and matter for relatives.
Localised LAMN / adenocarcinoma
- For my situation (localised lamn / adenocarcinoma), which of the standard options do you recommend and why?Why: Guideline options include: Appendicectomy (LAMN without perforation) or right hemicolectomy (adenocarcinoma, goblet cell); adjuvant chemotherapy for node-positive adenocarcinoma by colorectal analogy.
- Am I a candidate for FOLFOX (5-FU, leucovorin, oxaliplatin), CAPOX (capecitabine, oxaliplatin), and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Pseudomyxoma peritonei / peritoneal disease
- For my situation (pseudomyxoma peritonei / peritoneal disease), which of the standard options do you recommend and why?Why: Guideline options include: Cytoreductive surgery with HIPEC at a peritoneal-surface-malignancy centre; repeat CRS for recurrence when feasible.
High-grade or unresectable peritoneal disease
- For my situation (high-grade or unresectable peritoneal disease), which of the standard options do you recommend and why?Why: Guideline options include: FOLFOX/CAPOX ± bevacizumab; systemic chemotherapy has no proven benefit in low-grade disease (randomised 2024).
- Am I a candidate for FOLFOX (5-FU, leucovorin, oxaliplatin), CAPOX (capecitabine, oxaliplatin), Bevacizumab, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Any stage
- Are there clinical trials I could join, for example of HIPEC / PIPAC (intraperitoneal chemotherapy), FOLFOX (5-FU, leucovorin, oxaliplatin)?Why: Trials are how the next standard of care is set; asking early keeps options open.
- Would a second opinion at a high-volume centre change anything, and can you help arrange it?Why: Rare or high-stakes decisions benefit from a centre that treats many similar patients.
- What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?Why: Supportive care improves quality of life and helps patients complete treatment.
- I read that “No effective systemic therapy for high-grade or signet-ring disease”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
- I read that “Selection for CRS-HIPEC and management of recurrence after maximal surgery”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
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Direct links plus the targets, companies, and technologies of this cancer's products.
technologies
9targets
3drugs
5companies
2pathways
1terms
2Latest papers
topQuery for this cancer: (TITLE:"Appendiceal cancer and pseudomyxoma peritonei" OR ABSTRACT:"Appendiceal cancer and pseudomyxoma peritonei" OR TITLE:"Appendix cancer" OR ABSTRACT:"Appendix cancer" OR TITLE:"PMP" OR ABSTRACT:"PMP" OR TITLE:"Low-grade appendiceal mucinous neoplasm LAMN" OR ABSTRACT:"Low-grade appendiceal mucinous neoplasm LAMN") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Appendiceal cancer and pseudomyxoma peritonei, not a curated reading list.
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