Peritoneal Carcinomatosis – Causes, Symptoms & Treatment

What is Peritoneal Carcinomatosis?

Peritoneal carcinomatosis (also referred to as peritoneal metastasis) describes the spread of malignant tumor cells to the peritoneum – a thin tissue layer that lines the abdominal cavity and surrounds the internal organs. It represents a form of metastasis in which cancer cells from a primary tumor migrate into the abdominal cavity and establish secondary tumor deposits there. Peritoneal carcinomatosis is considered an advanced stage of cancer and presents a significant challenge in oncological treatment.

Causes and Development

Peritoneal carcinomatosis develops when tumor cells from a primary cancer spread into the abdominal cavity. This can occur through several mechanisms:

• Direct invasion: A tumor grows through the wall of an organ and reaches the peritoneum.
• Hematogenous or lymphogenous spread: Tumor cells are transported via blood or lymphatic vessels.
• Intraperitoneal dissemination: Tumor cells detach from the primary lesion and are distributed throughout the abdominal cavity via ascitic fluid.

The most common primary tumors leading to peritoneal carcinomatosis include:

• Colorectal carcinoma (colon and rectal cancer)
• Gastric carcinoma (stomach cancer)
• Ovarian carcinoma
• Pancreatic carcinoma
• Appendiceal carcinoma (e.g., pseudomyxoma peritonei)
• Less commonly: bladder, uterine, or liver cancer

Symptoms

In early stages, peritoneal carcinomatosis often causes no or only nonspecific symptoms. As the disease progresses, the following symptoms may develop:

• Abdominal pain and a feeling of pressure in the abdomen
• Ascites (fluid accumulation in the abdomen, visible abdominal distension)
• Bloating, nausea, and vomiting
• Changes in bowel habits (constipation or diarrhea)
• Unintentional weight loss
• Loss of appetite and general fatigue
• Ileus (bowel obstruction) as a serious complication

Diagnosis

The diagnosis of peritoneal carcinomatosis is established through a combination of investigations:

Imaging Methods

• CT (computed tomography): The most commonly used method for assessing the extent of abdominal spread
• MRI (magnetic resonance imaging): Used as a complement, particularly for soft tissue evaluation
• PET-CT: For assessment of metabolic activity within tumor lesions

Additional Diagnostic Measures

• Laparoscopy: Direct visual inspection of the abdominal cavity and tissue biopsy
• Paracentesis: Analysis of ascitic fluid for tumor cells (cytology)
• Tumor markers in the blood (e.g., CEA, CA-125, CA 19-9)

To quantify the extent of the disease, the Peritoneal Cancer Index (PCI) developed by Sugarbaker is widely used. It evaluates tumor burden across 13 abdominal regions, yielding a score from 0 to 39.

Treatment

Treatment of peritoneal carcinomatosis depends on the primary tumor type, the extent of disease, the overall health of the patient, and the therapeutic goals. Treatment approaches can be broadly divided into curative and palliative strategies.

Cytoreductive Surgery (CRS)

In carefully selected patients, cytoreductive surgery is performed to remove all visible tumor deposits from the abdominal cavity. The goal is complete or near-complete tumor reduction (cytoreduction).

HIPEC (Hyperthermic Intraperitoneal Chemotherapy)

Cytoreductive surgery is frequently combined with HIPEC. In this procedure, a chemotherapy solution heated to approximately 41–43 °C is administered directly into the abdominal cavity immediately after surgery. The heat enhances the effectiveness of the chemotherapy against remaining tumor cells and improves the penetration of the drug into surrounding tissue.

Systemic Chemotherapy

In cases where surgery is not feasible, or as an adjunct to surgery, systemic chemotherapy is used. The regimen depends on the primary tumor (e.g., FOLFOX or FOLFIRI for colorectal cancer, carboplatin/paclitaxel for ovarian cancer).

Targeted Therapy and Immunotherapy

Depending on tumor biology, targeted therapies (e.g., bevacizumab, cetuximab) or immunotherapies (e.g., immune checkpoint inhibitors) may also be employed.

Palliative Measures

In advanced disease, the focus shifts to relieving symptoms and improving quality of life. This includes management of ascites, pain therapy, and nutritional support.

Prognosis

The prognosis of peritoneal carcinomatosis depends strongly on the primary tumor type, the PCI score, and the treatment approach. In carefully selected patients who undergo complete cytoreductive surgery combined with HIPEC, studies have demonstrated significantly improved survival times compared to systemic chemotherapy alone. Early diagnosis and interdisciplinary management at a specialized center are key determinants of treatment outcomes.

References

1. Sugarbaker, P.H. (2016): Peritoneal Surface Oncology. Springer Verlag.
2. Verwaal, V.J. et al. (2003): Randomized trial of cytoreduction and hyperthermic intraperitoneal chemotherapy versus systemic chemotherapy and palliative surgery in patients with peritoneal carcinomatosis of colorectal cancer. Journal of Clinical Oncology, 21(20), 3737–3743.
3. National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology: Colon Cancer (2023). Available at: https://www.nccn.org