Peritoneal Sarcoma

Peritoneal sarcoma is a rare type of cancer that develops when sarcoma tumors appear in or spread to the peritoneum, the thin lining inside the abdomen that covers organs and produces lubricating fluid.

Table of contents

• What is Peritoneal Sarcoma?
• Types of Sarcoma in the Peritoneum
• Signs and Symptoms
• How is it Diagnosed?
• Treatment Options
• Outlook and Prognosis

What is Peritoneal Sarcoma?

Peritoneal sarcoma occurs when sarcoma (a type of cancer that develops in soft tissues like muscles or fat) appears inside the peritoneal cavity. The peritoneum is the membrane that lines your abdomen and pelvis, covering important organs such as the kidneys, pancreas, bladder, and major blood vessels^[3].

This condition is quite rare. When sarcoma develops in the peritoneal area, it is called peritoneal sarcomatosis. The presentation of sarcoma inside the peritoneal cavity is a rare finding to begin with, and there are many different subtypes of sarcoma that can be identified in this location, each with different characteristics in terms of outlook and treatment options^[5].

Types of Sarcoma in the Peritoneum

The types of sarcoma that occur most commonly in the retroperitoneum (the deep space in the abdomen behind the abdominal lining where organs are located) include^[3]:

• Liposarcoma – cancer of the fatty tissues
• Leiomyosarcoma – cancer of the involuntary muscle

Other less common types found in the peritoneal area include solitary fibrous tumor, pleomorphic sarcoma, malignant peripheral nerve sheath tumor, synovial sarcoma, and Ewing sarcoma^[3].

Approximately 15 percent of soft tissue sarcomas arise in the retroperitoneum. About one third of malignant tumors that appear in this deep abdominal space are sarcomas^[6].

• Peritoneum
• Retroperitoneum
• Kidneys
• Pancreas
• Bladder
• Major blood vessels
• Colon
• Spleen

Signs and Symptoms

Symptoms of peritoneal sarcoma can vary depending on the size and location of the tumor. Many people do not notice symptoms until the disease has advanced because tumors in this area can grow quite large before causing noticeable problems^[3][6].

Retroperitoneal sarcomas smaller than five centimeters are rarely seen because patients usually don’t notice them until they become larger^[6]. Retroperitoneal sarcomas most commonly present as an abdominal mass, often without other symptoms^[11].

Common symptoms may include^[3][11]:

• A noticeable lump in the abdomen
• Increase in abdominal girth
• Dull pain in the abdomen or back
• Abdominal mass
• Loss of appetite or weight loss
• Early satiety (feeling full after eating only a small amount of food)
• Blood in stools
• Lower extremity swelling
• Pain

Other rare symptoms include hernia or anemia. When symptoms are present, they relate to the mass effect of the tumor or to local invasion of nearby tissues^[11].

How is it Diagnosed?

A diagnosis of peritoneal sarcoma may start with a visit to your doctor, who will then refer you to a specialist. Some peritoneal sarcomas are discovered through investigations for another medical condition or are diagnosed after surgery for a different problem^[3].

Your symptoms will be investigated using a series of tests. These may include^[3][11]:

Physical examination – Your doctor will look at and feel any lump or abnormality in your abdomen.

Imaging scans – A computed tomography scan (CT scan) is the most useful diagnostic tool for peritoneal sarcoma^[11]. Other tests may include taking pictures of the inside of the body using ultrasound, x-ray, or MRI (magnetic resonance imaging).

Biopsy – A tissue sample is taken and tested. Core needle biopsies use a hollow needle to remove the tissue. A clear diagnosis will be made after a specialist with experience in sarcoma has examined the tissue sample^[3].

The biopsy can help tell the difference between sarcoma and other conditions occurring in the abdomen. It can also help decide the correct treatment for the condition^[3].

Treatment Options

Surgery

Surgery is the main treatment for peritoneal sarcoma. The surgeon will remove the tumor and will aim to take out an area of normal tissue around it when possible. This is known as taking a margin^[3][11].

Peritoneal sarcomas can sometimes touch or press on surrounding organs. In these cases, the surgeon will aim to remove the tumor along with any organs next to it “en bloc,” meaning as a whole. Depending on the size and location of the tumor, the surgery may involve removing part of or whole organs such as the kidney, colon (bowel), pancreas, spleen, or bladder, which can have implications on your quality of life^[3].

Your surgeon will explain if this is required and the implications of removing the organ attached or next to your tumor. A small number of people will need a colostomy (an opening between the intestine and outside of the body) or urostomy (a similar opening for urine) following surgery^[3].

In cases where it is not possible to remove the tumors completely, surgery is unlikely to be recommended^[3].

Radiation and Chemotherapy

Survival rates are affected by the large tumor size at presentation, the inability to achieve wide surgical margins, and the limitations of treating peritoneal sarcoma with radiation and chemotherapy^[6].

The treatment you receive should take into account your individual situation. Your doctor or clinical nurse specialist should discuss with you the available options^[3].

Outlook and Prognosis

Evaluation and treatment of peritoneal sarcomas are challenging because these tumors are relatively rare and frequently present with advanced disease in an anatomically complex location^[6].

The outlook varies depending on several factors. Survival rates are affected by the large tumor size when patients first seek care, the difficulty in achieving wide surgical margins around the tumor, and the limitations of radiation and chemotherapy treatments in this area^[6].

Although the median patient age is approximately fifty years, peritoneal sarcomas can occur at any age and arise equally in women and men^[11].

Because there are many different subtypes of sarcoma that can appear in the peritoneum, each presenting with different characteristics in terms of prognosis and treatment options, the resulting lack of strong data makes treatment planning challenging^[5].