Peritoneal mesothelioma is a rare but aggressive cancer that primarily affects the abdominal lining. It is a type of cancer that originates in the peritoneum (membrane that lines the abdominal cavity). It typically presents with abdominal pain, distension, and accumulation of fluid in the abdomen region(ascites).

Overview

Peritoneal mesothelioma is a specific type of cancer that originates in the peritoneum. The peritoneum is a thin and protective membrane that lines the abdominal cavity and covers most of the organs in the abdomen. It has a vital role in facilitating the smooth movement of organs, providing lubrication, and supporting their functions. In peritoneal mesothelioma, cancerous cells develop within the peritoneum and form tumours or diffuse masses on the surface of abdominal organs. When cancer develops in this delicate tissue, it can lead to a range of health issues and complications. Mesothelioma is a rare and aggressive form of cancer that affects the mesothelial lining of various organs in the body. Among the different types of mesotheliomas, peritoneal mesothelioma is relatively less common but equally devastating. Due to its rarity and nonspecific symptoms, it is usually diagnosed late, when the disease burden is extensive, and the therapy is inevitably palliative.¹

Causes of peritoneal mesothelioma

The primary cause of peritoneal mesothelioma is exposure to asbestos. Asbestos is a group of naturally occurring minerals known for their heat resistance, durability, and fireproofing properties. A very large majority of cases of mesothelioma is caused by asbestos exposure [Malignant mesothelioma 2010]. Historically, asbestos was used in various industries, including construction, shipbuilding, automotive manufacturing, and insulation. Workers in these fields were frequently exposed to asbestos fibres, which could become airborne and easily inhaled or ingested. Exposure to asbestos could be from:

• Occupational Exposure- Workers who directly handled asbestos-containing materials, such as construction workers, shipbuilders, and insulators, faced a high risk of asbestos exposure.
• Environmental Exposure- Asbestos-containing materials in homes, schools, and older buildings can deteriorate over time, releasing asbestos fibres into the air. Natural disasters, like hurricanes or earthquakes, can also release asbestos fibres from damaged structures.
• Secondary Exposure- Family members of individuals who worked with asbestos could unknowingly be exposed to the asbestos fibres brought home on contaminated clothing and tools, leading to secondary exposure. 

Aside from asbestos exposure, there are other potential risk factors, although they are less understood. Genetic predisposition and exposure to radiation have also been suggested as possible contributors to the development of peritoneal mesothelioma.

Signs and symptoms

Peritoneal mesothelioma often presents a unique set of symptoms that can be challenging to distinguish from other abdominal issues. Some of the common signs and symptoms include:² 

• Abdominal Pain: Dull, aching pain in the abdomen is a frequent complaint.
• Abdominal Swelling: Accumulation of fluid in the abdominal cavity, known as ascites, can lead to noticeable swelling.
• Unexplained Weight Loss: Significant and unexplained weight loss is often a red flag.
• Nausea and Vomiting: These symptoms can occur due to pressure on the stomach or intestines.
• Changes in Bowel Habits: Altered bowel movements may occur.
• Fatigue: Patients may experience extreme tiredness.
• Anaemia: A decrease in red blood cell count can lead to fatigue and weakness.

These symptoms are often nonspecific and can be attributed to various gastrointestinal or abdominal issues, leading to delayed diagnosis.

Diagnosis

Diagnosing peritoneal mesothelioma can be challenging due to its rarity and the similarity of its symptoms to other conditions. The precise diagnosis of peritoneal mesothelioma is based on a detailed medical history, followed by radiological, laboratory, and pathological examinations. Computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET) are the main imaging modalities used.³ The diagnostic process typically involves the following steps:

1. Medical History and Physical Examination- The doctor will inquire about the patient's medical history and perform a physical examination to assess symptoms.
2. Imaging Tests- CT scans and MRIs are commonly used to visualize the abdominal region and identify abnormalities.
3. Biopsy- A biopsy is the definitive diagnostic tool. It involves the removal of a small tissue sample for microscopic examination. A pathologist can confirm the presence of cancer cells.
4. Blood Tests- Blood tests, including measurement of biomarkers like CA-125, may be used to support the diagnosis.

Once diagnosed, peritoneal mesothelioma is often staged to determine the extent of the disease and guide treatment decisions. Stages range from I to IV, with IV being the most advanced.

Staging and prognosis

Prognosis for peritoneal mesothelioma varies based on the stage at diagnosis. However, it's important to understand that this cancer generally has a poor prognosis due to its aggressive nature. The stages are as follows:

Stage I: Cancer is localized to the peritoneum.

Stage II: Cancer has spread to nearby tissues and lymph nodes.

Stage III: Cancer has spread further into the abdomen or lymph nodes.

Stage IV: Cancer has metastasized to distant organs.

Survival rates for peritoneal mesothelioma tend to be lower compared to other cancers. However, advances in treatment options and early detection efforts provide hope for improved outcomes.

Treatment options

The treatment approach for peritoneal mesothelioma is complex and often involves a combination of therapies. The specific treatment plan depends on factors like the stage of the cancer and the patient's overall health. Common treatment options include:

• Surgery:
  • Cytoreductive surgery aims to remove as much of the tumour as possible from the peritoneal cavity.
  • Hyperthermic Intraperitoneal Chemotherapy (HIPEC) is often performed alongside surgery to deliver heated chemotherapy directly to the abdominal cavity.
• Chemotherapy: Chemotherapy drugs, such as pemetrexed and cisplatin, may be used to target cancer cells and slow tumour growth.
• Radiation Therapy: Radiation therapy may be utilized to shrink tumours or relieve symptoms in some cases.
• Emerging Therapies: Clinical trials are exploring innovative treatments, including immunotherapy and targeted therapies, to improve outcomes for peritoneal mesothelioma patients.
• Palliative Care: In cases where a cure is not possible, palliative care plays a crucial role in managing symptoms, providing pain relief, and enhancing the patient's overall quality of life. Palliative care specialists work alongside the medical team to ensure the patient's comfort and emotional well-being.

 A diagnosis of peritoneal mesothelioma can be overwhelming, not only for the patient but also for their loved ones. Coping strategies, emotional support, and participation in support groups can significantly help individuals navigate the physical and emotional challenges associated with this rare cancer.

Prevention and awareness

Preventing peritoneal mesothelioma primarily involves avoiding asbestos exposure. This includes taking precautions when working with asbestos-containing materials, being aware of environmental risks, and seeking prompt medical attention if exposure is suspected. Raising awareness about the dangers of asbestos and the signs of mesothelioma is crucial for early detection and improved outcomes.

Conclusion

Peritoneal mesothelioma may be rare, but it carries significant implications for those affected by it. As our understanding of this cancer continues to evolve, early detection and advances in treatment options offer hope to individuals battling peritoneal mesothelioma. While its prognosis is often challenging, advances in treatment options and early detection efforts offer hope to those affected by this disease. By shedding light on its causes, symptoms, diagnosis, and potential treatments, we can contribute to better outcomes and improved quality of life for patients facing this challenging disease.