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Teaching pack: Appendiceal cancer and pseudomyxoma peritonei

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  1. Teaching pack · Cancer · gastrointestinal

    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.

    Teaching pack: Appendiceal cancer and pseudomyxoma peritonei · OnCo, CC BY 4.0 · not medical advice1 / 8
  2. What it is

    In two paragraphs

    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.

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  3. Standard of care

    What is given today, by setting

    SettingApproachGuideline
    Localised LAMN / adenocarcinomaAppendicectomy (LAMN without perforation) or right hemicolectomy (adenocarcinoma, goblet cell); adjuvant chemotherapy for node-positive adenocarcinoma by colorectal analogy.NCCN Category 2A
    Pseudomyxoma peritonei / peritoneal diseaseCytoreductive surgery with HIPEC at a peritoneal-surface-malignancy centre; repeat CRS for recurrence when feasible.not mapped
    High-grade or unresectable peritoneal diseaseFOLFOX/CAPOX ± bevacizumab; systemic chemotherapy has no proven benefit in low-grade disease (randomised 2024).not mapped
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  4. State of the art

    Where the field stands

    • CRS-HIPEC turned PMP from a fatal disease into one with long survival for low-grade histology.
    • 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.
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  5. History

    How we got here

    1. 1842Rokitansky describes a mucocele of the appendix
    2. 1884Werth coins 'pseudomyxoma peritonei'
    3. 1995Sugarbaker's peritonectomy procedures and HIPEC
    4. 2012Multi-institutional CRS-HIPEC outcomes: 10-year survival 63% (Chua, JCO)
    5. 2016PSOGI classification of appendiceal mucinous neoplasms and PMP
    6. 2024Randomised trial: no benefit of systemic chemotherapy in low-grade mucinous carcinoma peritonei
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  6. Pipeline

    What is coming

    • HIPEC / PIPAC (intraperitoneal chemotherapy) (technology)
    • FOLFOX (5-FU, leucovorin, oxaliplatin) (product)
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  7. Open problems

    What nobody has solved

    • 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.
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  8. Sources

    Read the primary sources

    • PSOGI consensus (Am J Surg Pathol 2016): https://doi.org/10.1097/PAS.0000000000000535
    • Appendix Cancer / PMP Research Foundation: https://www.acpmp.org/
    • NCI: appendix cancer: https://www.cancer.gov/pediatric-adult-rare-tumor/rare-tumors/rare-digestive-system-tumors/appendix-cancer
    • Wikipedia: https://en.wikipedia.org/wiki/Pseudomyxoma_peritonei
    • Guideline: https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1428
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