Peritoneal mesothelioma attacks the membranous lining of the abdomen, called the peritoneum. Ten to twenty percent of all malignant mesothelioma cases are peritoneal mesothelioma. Like all malignant mesothelioma cancers, peritoneal mesothelioma is caused by exposure to deadly asbestos fibers. It is thought to develop when victims breathe in the tiny fibers, and then cough them up and swallow them. The minute fibers may also be ingested with food or drink, or they may be inhaled and wind up in the abdomen via the lymphatic system. The asbestos fibers stick to the lining and become lodged between the cells that make up the lining of the abdomen. Malignant mesothelioma develops slowly over decades and is usually discovered in its late stages, which limits treatment options.
Peritoneal mesothelioma is one type of malignant mesothelioma, the other types being pleural mesothlioma, pericardial mesothelioma and testicular mesothelioma.
Treatment options include surgery, chemotherapy, and radiation, alone or in any combination. Because there is no effective early detection screening procedure and peritoneal mesothelioma is difficult to identify until the tumors grow large enough to cause discomfort or flood the abdomen with fluid, it is rarely diagnosed early enough to cure. However, recent research focused on early detection using blood markers is encouraging. We may see blood screenings for early detection of malignant mesothelioma in just a few years.
Types of Peritoneal Mesothelioma Surgery
Three types of surgery are used in the diagnosis and treatment of peritoneal mesothelioma.
- Biopsy is a procedure often used to confirm the diagnosis of peritoneal mesothelioma. It is a non-invasive surgical procedure where a surgeon uses a long, thin needle to scrape out cells from the affected area for testing.
- Removing as much cancerous tissue as possible is called curative surgery. Recent advances in curative surgery combine heated chemotherapy drugs introduced to the abdominal cavity immediately after surgery to kill any remaining cancer.
- Palliative peritoneal surgery is used to relieve pain and other symptoms.
Surgery
Several biopsy procedures may be used to confirm a diagnosis of peritoneal mesothelioma and determine the extent of the disease.
During a fine needle aspiration, or laparoscopy, the oncology surgeon inserts a thin needle into the abdominal area where cancer is suspected and nips a small sample of tissue for testing.
If the results of the needle aspiration are inconclusive, the surgeon may perform a peritoneoscopy. A local anesthetic is administered for this procedure, and then the surgeon makes a small incision and inserts a tool called a peritoneoscope that allows him to see inside the abdomen with a light and a tiny camera attached to flexible tubing. A tissue sample is often collected during this exploration. In some cases, a more invasive biopsy is called for, and the surgeon may make a larger incision to collect additional tissue.
There are two linings that make up the peritoneum, called the visceral and parietal peritoneum. The visceral peritoneum protects the internal organs and the intestinal tract. The parietal peritoneum covers the abdominal cavity. The cells that make up these linings secret a fluid that lubricates the organs, allowing free movement without friction, much like oil lubricates the moving parts of an automobile. Cancerous cells from peritoneal mesothelioma cause cells to overproduce, flooding the abdominal cavity with fluid. Oncologists use a long needle attached to tubing with a bag at the end to drain the fluid. This procedure serves two purposes. It relieves the pressure of the excess fluid to make the patient more comfortable, and the fluid is analyzed to add to the physician’s store of knowledge about the patient’s condition. This procedure is called an adoparacentesis or peritoneal aspiration.
Peritonectomy
If peritoneal mesothelioma is detected early, a peritonectomy may be performed. This surgery involves removing all or part of the diseased peritoneum. This is often combined with intraperitoneal hypothermic perfusion or bathing the abdominal cavity with heated chemotherapy immediately following surgery to kill any remaining cancer.
Cytoreductive Surgery
Cytoreductive surgery, also called debulking, is used to remove only the cancerous tissues and tumors. The surgeon opens a large incision in the patient’s abdomen and carefully removes the visible infected cells, then often follows the procedure with intraperitoneal hypothermic perfusion.
Not every patient is a candidate for surgery. The cancer has to be in the early stages so that enough healthy tissue remains to allow the body to function, and the patient has to be strong enough to withstand the procedure before it can be considered.
Chemotherapy
Chemotherapy refers to chemical treatments designed to kill cells and may take the form of pills, injections, intravenous treatments or delivered directly into the body cavity during surgery. Chemotherapy has many unpleasant side effects and is not suitable for patients already in poor health.
Chemotherapy drugs may be used alone or with other drugs, surgery or treatments. While chemotherapy is not a cure for malilgnant mesothelioma, the treatment is used to help slow the growth of the cancer. Other chemotherapy goals are neoadjuvant therapy, used to shrink tumors prior to surgery, adjuvant therapy to destroy tumorous cells following surgery, and palliative therapy to relieve symptoms that cause pain and discomfort to the patient.
It is important for patients to be completely honest about prescriptions, vitamins, supplements and over-the-counter medications, including herbal remedies when discussing chemotherapy with an oncologist. The more information the doctor has, the better the advice he can give.
Radiation
Ionizing radiation is a therapy used to kill existing cancer cells and prevent the cancer from spreading. It may be used by itself or in combination with chemotherapy and/or surgery. Radiation may be curative, to kill the cancer, or palliative, to reduce tumors and make the patient more comfortable. Two types of radiation therapy are used to treat malignant mesothelioma: external beam radiotherapy and brachytherapy.
External beam radiotherapy is the most frequently used radiation therapy for malignant mesothelioma patients. It is an external treatment where the exposed skin over the cancerous area, the abdominal area in the case of peritoneal mesothelioma is irradiated. External beam radiotherapy is not specifically targeted enough to kill all cancer cells, and is most often used in conjunction with other forms of therapy to relieve symptoms and reduce pressure. During this procedure, tissue around the affected area is equally exposed and side effects typically result that include skin irritation, pain, and difficulty swallowing.
Brachytherapy involves implanting tiny radioactive rods, sometimes called seeds, directly into the cancerous area. This delivery method delivers a tiny dose of radiation directly into the cancerous tumors. Less damage is done to surrounding healthy tissues and as a result, there are fewer side effects.
Intensity-modulated radiation therapy (IMRT) is a new procedure involving an advanced mode of delivering computer-controlled, high-precision radiotherapy. IMRT carefully controls the dose of radiation to conform precisely to tumors using three-dimensional (3-D) modeling. This allows a higher dose of radiation, tightly focused on diseased cells, while minimizing impact on healthy surrounding tissues and, as a result, minimizing side effects
