PERITONEAL CARCINOMATOSIS —Revision sheet for Students

1. Primary peritoneal cancer or carcinoma was historically classified under “carcinoma of unknown primary”. Primary peritoneal cancer is a cancer of the cells lining the peritoneum, or abdominal cavity. It usually affects women and is diagnosed after the age of 60; it very rarely affects men.

What you normally come across is “Secondary Peritoneal Cancer”

Secondary Peritoneal Cancer:

1. Definition: Metastatic spread of cancer to the peritoneum – It is most frequently from intra‑abdominal cancers (Primary Site):

Common Primary Tumors:

1. Ovary –  Most common cause
2. Colon/Rectum – Common GI source
3. Stomach – Often aggressive
4. Pancreas – Poor prognosis
5. Appendix – Includes pseudomyxoma peritonei
6. 10% originate outside the abdomen via blood/lymphatic spread.

Pathophysiology: – Tumor cells reach peritoneum via:

1. Transcoelomic spread  (most common)
2. Direct invasion
3. Lymphatic/hematogenous spread

Clinical Features: Usually – late presentation

1. Ascites – (hallmark) Key symptom
2. Abdominal distension
3. Abdominal pain / palpable mass
4. Fatigue
5. Nausea/vomiting
6. Constipation
7. Low back pain
8. Unexplained weight loss or gain

  Diagnosis: 1) Imaging:

• CT scan – (first‑line)
• MRI
• PET scan

Laboratory Investgations:

• Blood Test for Tumour Markers (CA- 125, CEA)

Procedures:

1. Paracentesis: Check Cytology of ascitic fluid
2. Biopsy: Confirms malignancy and helps identify primary

Peritoneal Carcinomatosis Index (PCI) – (for Prognosis)

Scores based on tumour Size & Distribution (across 13 abdominal regions-9 zones of abdomen + Upper Jejunum, Lower jejunum, Upper ileum & Lower ilium).

– **Higher PCI = worse prognosis + lower chance of complete cytoreduction.**

Management

1. Curative‑intent approach: “CRS (Cytoreductive Surgery) + HIPEC”    *CRS:** Remove all visible peritoneal disease **HIPEC:** Heated intraperitoneal chemotherapy to kill microscopic residual cells – More effective than systemic chemotherapy for peritoneal spread
2. Additional therapy: Continue treatment for “Primary Cancer”
3. Palliative care– For non‑surgical candidates  –  Symptom control (ascites, pain, nutrition)

Complications of CRS + HIPEC

• Hemorrhage
• Bowel perforation
• Anastomotic leak
• Infection / abscess
• Sepsis
• Rare perioperative mortality

Prognosis: No cure, but CRS + HIPEC improves survival.

Five Year Survival Outcome:

• Complete cytoreduction achieved –      45% 5 yr Survival
• Residual disease remains –                     <10% survive 5 yrs

Final Prognostic factors:

• Primary cancer type
• Tumor grade
• Symptom severity
• PCI score
• Completeness of cytoreduction