Peritoneal Surface Malignancies

If you or a loved one have been told that you have a peritoneal surface malignancy, you may wonder what that is. This is any cancer that affects the peritoneum, a membrane that lines the abdomen. A peritoneal surface cancer is also called a peritoneal carcinomatosis (PC).

The peritoneum is a very complex membrane. It has an outer layer called the parietal peritoneum that is attached to the abdominal and pelvic walls. It also has an inner layer – the visceral peritoneum – that is wrapped around some of the abdominal organs. The space between these two layers is called the peritoneal cavity. It is filled with a fluid that lubricates the layers and allows them to slide past each other. (See a diagram of the peritoneum.) Unfortunately, this fluid also allows cancers in the peritoneum to easily spread along the membrane's large surface area.

Where do peritoneal tumors originate?

Most cancers in the peritoneum begin in another part of the body. Cancers of the appendix, colon, rectum, stomach and ovaries commonly spread to the nearby peritoneum. However, breast cancer and other cancers originally outside of the abdomen can also spread to the peritoneal membrane.

Often, a recurrence of an abdominal cancer will present as a peritoneal cancer. In rare cases (fewer than 7 cases per 1 million people each year), a cancer will start in the peritoneum. These tumors include primary peritoneal serous carcinoma (PPSC) and peritoneal mesothelioma. Diagnosis of a primary tumor in the peritoneum can be difficult; primary peritoneal tumors are sometimes misdiagnosed as adenocarcinomas of unknown primary. An experienced pathology team can perform the extensive workup with immunomarkers necessary for arriving at the correct diagnosis.

How are peritoneal tumors treated?

For many years, peritoneal surface malignancies were considered inoperable. This is because the peritoneum extends over a large area and also because these cancers tend to affect multiple organs. Performing surgery to remove the cancer would be a long, complex process. The risks associated with operating on several organs were not thought to be worth the limited benefits of the surgery.\

Also, because the peritoneum is almost completely divided from the bloodstream (this is called the peritoneal-plasma barrier), chemotherapy delivered through an IV has little effect in treating these cancers.

Thanks to advances in surgical techniques and tools, today a procedure called cytoreductive surgery (CRS) can be used to treat peritoneal tumors. With this approach, the surgeon removes as many cancer cells as possible. CRS is often combined with heated chemotherapy (HIPEC) applied directly to the surgical site. HIPEC overcomes the peritoneal-plasma barrier and kills many of the microscopic cancer cells that have been left behind after surgery.