Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei
Low-grade appendiceal mucinous neoplasm is a slow-growing appendiceal cancer that makes mucus, and when it bursts it spreads jelly through the abdomen as pseudomyxoma peritonei. It rarely spreads through blood or lymph, so it is treated by stripping all visible disease from the abdomen and washing the cavity with heated chemotherapy, an operation that gives most patients many years of life.
Overview
Low-grade appendiceal mucinous neoplasms (LAMN) are villous or flat mucinous tumours that grow inside the appendix without invading its wall in the way a carcinoma does, distend it into a mucocele and, if they perforate, release mucin and tumour cells into the peritoneal cavity. There they redistribute along the flow of peritoneal fluid to the omentum, pelvis, right diaphragm and liver surface, producing pseudomyxoma peritonei, a slowly enlarging accumulation of mucin that eventually compresses the bowel and starves the patient. The PSOGI consensus of 2016 classifies the peritoneal disease as acellular mucin, low-grade, high-grade or high-grade with signet ring cells, and grade is the strongest predictor of survival; GNAS mutations are typical of low-grade disease, while TP53 and SMAD4 mark high-grade change. A LAMN confined to the appendix without perforation is cured by appendicectomy, and right hemicolectomy adds nothing.
Once the peritoneum is involved the treatment is cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC), developed by Paul Sugarbaker in the 1980s and 1990s: every visible deposit is removed by peritonectomy and organ resection, and the abdomen is then perfused with heated mitomycin (or oxaliplatin) for 60 to 90 minutes. A multi-institutional registry of 2,298 patients (Journal of Clinical Oncology 2012) reported a median survival of 16.3 years and 10-year survival of 63 percent after complete cytoreduction, and the operation is standard in specialist centres although it has never been compared with lesser surgery in a randomised trial. Systemic chemotherapy has little effect on low-grade disease, and a randomised trial at MD Anderson found no benefit from fluoropyrimidine-based chemotherapy over observation in unresectable low-grade mucinous adenocarcinoma, so it is kept for high-grade histology. Patients with recurrence can be operated again, and those with unresectable disease are managed by debulking for symptoms, and in trials by mucolytic agents such as bromelain with acetylcysteine and by pressurised intraperitoneal aerosol chemotherapy.
State of the art
- The PSOGI classification made grade the basis of treatment decisions across centres.
- Chemotherapy has no proven role in low-grade disease, sparing patients its toxicity.
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.
- Cytoreductive surgery with HIPEC gives long survival in low-grade pseudomyxoma peritonei and is the model for peritoneal surface oncology.
Red cards
From the labels and guidelines behind the standard of care. Your team's thresholds win.- Emergency services nowBleeding or bruising
Bleeding that will not stop, black or bloody stools, or unexplained bruising when platelets are expected to be low.
See all on the product pages:CAPOX (capecitabine, oxaliplatin)FOLFOX (5-FU, leucovorin, oxaliplatin)Mitomycin C·Printable cards in the navigator
Anatomy and lymph node drainage
- Right colon (MSI-high, BRAF commoner)
- Left colon and sigmoid
- Rectum
- Anal canal (HPV squamous)
- Appendix
- Peritoneum and omentum (mesothelioma, peritoneal spread)
- Nodes: pericolic
- Nodes: mesenteric root
- Nodes: para-aortic
- Nodes: mesorectal
- Nodes: lateral pelvic and inguinal (anal)
Right-sided tumours behave differently from left-sided and rectal ones; the colon drains along its mesenteric vessels, the rectum into the mesorectum and pelvic side wall.
- Right colon (MSI-high, BRAF commoner)Low-grade appendiceal mucinous neoplasm confined to the appendix (cured by appendicectomy) · Low-grade pseudomyxoma peritonei (low-grade mucinous carcinoma peritonei) · High-grade appendiceal mucinous neoplasm (HAMN) and high-grade pseudomyxoma peritonei
- Left colon and sigmoid
- Rectum
- Anal canal (HPV squamous)
- AppendixLow-grade appendiceal mucinous neoplasm confined to the appendix (cured by appendicectomy) · LAMN with acellular mucin outside the appendix (low recurrence risk, surveillance) · Low-grade pseudomyxoma peritonei (low-grade mucinous carcinoma peritonei) · High-grade appendiceal mucinous neoplasm (HAMN) and high-grade pseudomyxoma peritonei · Pseudomyxoma peritonei with signet ring cells (worst grade) · Recurrent pseudomyxoma peritonei after cytoreductive surgery
- Peritoneum and omentum (mesothelioma, peritoneal spread)Low-grade pseudomyxoma peritonei (low-grade mucinous carcinoma peritonei) · High-grade appendiceal mucinous neoplasm (HAMN) and high-grade pseudomyxoma peritonei · Pseudomyxoma peritonei with signet ring cells (worst grade) · Recurrent pseudomyxoma peritonei after cytoreductive surgery
- pericolic
- mesenteric root
- para-aortic
- mesorectal
- lateral pelvic and inguinal (anal)
Same organ: Peritoneal mesothelioma, Colorectal cancer, Rectal cancer, Mismatch-repair deficient (MSI-high) colorectal cancer, BRAF V600E-mutant colorectal cancer, HER2-amplified colorectal cancer, KRAS G12C-mutant colorectal cancer, Early-onset colorectal cancer (under 50), Anal cancer (squamous cell carcinoma), Appendiceal cancer and pseudomyxoma peritonei, Small intestine cancer (small bowel adenocarcinoma), Small intestinal neuroendocrine tumours, Anal high-grade squamous intraepithelial lesions (precursor), Localised anal squamous cell carcinoma (stage I to III), Metastatic and recurrent anal squamous cell carcinoma, Appendiceal adenocarcinoma (mucinous and non-mucinous, including signet ring cell), Goblet cell adenocarcinoma of the appendix, Localised small bowel adenocarcinoma (stage I to III, resected), Advanced and metastatic small bowel adenocarcinoma
The commonest appendiceal neoplasm; most low-grade mucinous neoplasms are cured by appendicectomy, and the minority that rupture and seed the abdomen with mucin cause pseudomyxoma peritonei, which affects only a few people per million each year.
- MRIStandard of care
Nothing recorded yet.
Nothing recorded yet.
Also on OnCo: Symptoms and red flags · Early detection roadmap.
Cases by country
No country-level case numbers. This cancer is not mapped to a GLOBOCAN site.
One section per setting: the options named, what each is for, the trials behind them, the recorded trade-offs and the questions to ask.
Appendicectomy with clear margin; no right hemicolectomy; surveillance imaging if mucin was found outside the appendix.
Complete cytoreductive surgery (peritonectomy and organ resection) with hyperthermic intraperitoneal chemotherapy, mitomycin or oxaliplatin, in a specialist centre.
Cytoreductive surgery with HIPEC, with perioperative systemic chemotherapy (FOLFOX or CAPOX) as for appendiceal adenocarcinoma.
Repeat cytoreduction where feasible; debulking for symptoms; systemic chemotherapy only for high-grade histology; trials of mucolytics and pressurised intraperitoneal aerosol chemotherapy.
Subtypes & biomarkers
top- Low-grade appendiceal mucinous neoplasm confined to the appendix (cured by appendicectomy)
- LAMN with acellular mucin outside the appendix (low recurrence risk, surveillance)
- Low-grade pseudomyxoma peritonei (low-grade mucinous carcinoma peritonei)
- High-grade appendiceal mucinous neoplasm (HAMN) and high-grade pseudomyxoma peritonei
- Pseudomyxoma peritonei with signet ring cells (worst grade)
- Recurrent pseudomyxoma peritonei after cytoreductive surgery
- PSOGI grade of the peritoneal disease (acellular, low, high, signet ring)
- Peritoneal cancer index (extent) and completeness of cytoreduction score
- GNAS mutation (low grade), KRAS; TP53 and SMAD4 (high grade)
- CEA, CA 19-9 and CA-125 (prognosis and surveillance)
- Perforation and extra-appendiceal mucin on the appendicectomy specimen
How often this target appears
- 1884Werth coins the term pseudomyxoma peritonei
- 1995Sugarbaker describes peritonectomy procedures and heated intraperitoneal chemotherapy
- 2012International registry of 2,298 patients: median survival 16.3 years after cytoreduction and HIPEC
- 2016PSOGI consensus classification of appendiceal mucinous neoplasms and pseudomyxoma peritonei
- 2023Randomised trial finds no benefit from systemic chemotherapy in unresectable low-grade mucinous appendiceal adenocarcinoma
Dated changes read from the records linked to this cancer: approvals, regulatory steps, reported trials, guideline versions and milestones. Newest first; no date is inferred.
All 6 changes by month →- 2026-09-18This recordLow-grade appendiceal mucinous neoplasm and pseudomyxoma peritoneiFacts on this page last checked
When this page itself was last checked or edited.
- 2023MilestoneFOLFOX (5-FU, leucovorin, oxaliplatin)Randomised trial finds no benefit from systemic chemotherapy in unresectable low-grade mucinous appendiceal adenocarcinoma
A milestone in how this cancer is treated.
- 2016MilestoneLow-grade appendiceal mucinous neoplasm and pseudomyxoma peritoneiPSOGI consensus classification of appendiceal mucinous neoplasms and pseudomyxoma peritonei
A milestone in how this cancer is treated.
- 2012MilestoneHIPEC / PIPAC (intraperitoneal chemotherapy)International registry of 2,298 patients: median survival 16.3 years after cytoreduction and HIPEC
A milestone in how this cancer is treated.
- 1995MilestoneHIPEC / PIPAC (intraperitoneal chemotherapy)Sugarbaker describes peritonectomy procedures and heated intraperitoneal chemotherapy
A milestone in how this cancer is treated.
- 1884MilestoneLow-grade appendiceal mucinous neoplasm and pseudomyxoma peritoneiWerth coins the term pseudomyxoma peritonei
A milestone in how this cancer is treated.
What is in development for Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei, drawn from the whole corpus: 0 items. Drugs are grouped by the most advanced trial phase they have reached anywhere; approved treatments sit under standard of care. Technologies are the methods being tested for this cancer, trials are the studies recorded here, and ideas are proposals not yet in a trial.
Nothing recorded in development for this cancer yet.
Open problems and what is being done
Cytoreduction with HIPEC has never been compared with cytoreduction alone in this disease.
Recurrence after complete cytoreduction is common and criteria for reoperation vary.
and how the field plans to fix it →What is being done about thisRecurrence and residual diseaseAvailable now- Mitomycin CApproved
In trialsNothing recorded yet.
Ideas and roadmapsNothing recorded yet.
Also on OnCo: Treatment journeys · Survivorship planner.
No effective systemic therapy exists for low-grade disease.
Patients are often diagnosed late after years of abdominal distension.
and how the field plans to fix it →What is being done about thisFinding cancer earlierAvailable now- MRIStandard of care
In trialsNothing recorded yet.
Ideas and roadmapsNothing recorded yet.
Also on OnCo: Symptoms and red flags · Early detection roadmap.
Trials
topTrials recruiting now
Country and place are remembered in this browser only. A postcode is sent to OpenStreetMap's Nominatim service to find coordinates when you press the button; nothing else leaves your device.
Expert centres
topExpert centres
Milan · cancer center | Italy | none recorded | 0 | 1,280 | 18,342 | #27 | |
Guangzhou · hospital | China | none recorded | 0 | 1,245 | 12,931 | - | |
Rotterdam · cancer center | Netherlands | none recorded | 0 | 852 | 12,180 | - | |
Goyang · cancer center | South Korea | none recorded | 0 | 573 | 9,401 | - | |
Shanghai · hospital | China | none recorded | 0 | 464 | 6,795 | - | |
Rosemont, IL · consortium | United States | none recorded | 0 | 49 | 750 | - | |
Prague · consortium | Czechia | none recorded | 0 | not matched | - | - | |
Brussels · consortium | Belgium | none recorded | 0 | not matched | - | - | |
Denver, CO · consortium | United States | none recorded | 0 | not matched | - | - | |
Paris · consortium | France | none recorded | 0 | not matched | - | - |
These are the things we can measure; they are not a ranking of quality. Each column is a field on the institution record or a count over what OnCo has linked; a centre that treats many patients with Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei but is thinly recorded here will look small.
Not known: OnCo holds no case-volume or outcome figures for centres, so none are shown. Where a national audit or registry publishes them, the centre's page links to it. Default order: Newsweek rank, then trials for this cancer, then research output.
Questions to ask
topQuestions to ask your oncologist about Low-grade appendiceal mucinous neoplasm 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 grade of the peritoneal disease, Peritoneal cancer indexand completeness of cytoreduction score, GNAS mutation, KRAS; TP53 and SMAD4, CEA, CA 19-9 and CA-125, Perforation and extra-appendiceal mucin on the appendicectomy specimen), 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 Low-grade appendiceal mucinous neoplasm confined to the appendix, LAMN with acellular mucin outside the appendix, Low-grade pseudomyxoma peritonei.
- Is germline (inherited) genetic testing recommended for me or my family?Why: Inherited variants can change treatment and matter for relatives.
LAMN confined to the appendix
- For my situation (lamn confined to the appendix), which of the standard options do you recommend and why?Why: Guideline options include: Appendicectomy with clear margin; no right hemicolectomy; surveillance imaging if mucin was found outside the appendix.
Pseudomyxoma peritonei, resectable
- For my situation (pseudomyxoma peritonei, resectable), which of the standard options do you recommend and why?Why: Guideline options include: Complete cytoreductive surgery (peritonectomy and organ resection) with hyperthermic intraperitoneal chemotherapy, mitomycin or oxaliplatin, in a specialist centre.
- Am I a candidate for Mitomycin C, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
High-grade pseudomyxoma peritonei
- For my situation (high-grade pseudomyxoma peritonei), which of the standard options do you recommend and why?Why: Guideline options include: Cytoreductive surgery with HIPEC, with perioperative systemic chemotherapy (FOLFOX or CAPOX) as for appendiceal adenocarcinoma.
- 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.
Unresectable or recurrent disease
- For my situation (unresectable or recurrent disease), which of the standard options do you recommend and why?Why: Guideline options include: Repeat cytoreduction where feasible; debulking for symptoms; systemic chemotherapy only for high-grade histology; trials of mucolytics and pressurised intraperitoneal aerosol chemotherapy.
- Am I a candidate for FOLFOX (5-FU, leucovorin, oxaliplatin), 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), HIPEC perfusion pumps and PIPAC nebulisers?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 “Cytoreduction with HIPEC has never been compared with cytoreduction alone in this disease”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
- I read that “Recurrence after complete cytoreduction is common and criteria for reoperation vary”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
Newly diagnosed? Read the first 60 days with Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei, then print the one-page appointment sheet with room for the answers.
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Direct links plus the targets, companies, and technologies of this cancer's products.
technologies
8targets
1drugs
3terms
5key papers
2The names on an appendix or small bowel pathology report, and hence which OnCo subtype page applies, follow this classification.
Whether an appendiceal tumour is called LAMN or adenocarcinoma, and whether peritoneal disease is graded low or high, decides prognosis and treatment; this paper set those names.
Latest papers
topQuery for this cancer: (TITLE:"Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei" OR ABSTRACT:"Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei" OR TITLE:"LAMN" OR ABSTRACT:"LAMN" OR TITLE:"Pseudomyxoma peritonei" OR ABSTRACT:"Pseudomyxoma peritonei" OR TITLE:"PMP" OR ABSTRACT:"PMP" OR TITLE:"Low-grade mucinous carcinoma peritonei" OR ABSTRACT:"Low-grade mucinous carcinoma peritonei" OR TITLE:"Disseminated peritoneal adenomucinosis" OR ABSTRACT:"Disseminated peritoneal adenomucinosis") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei, not a curated reading list.
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