Though we have looked in detail about mesothelioma in general and the treatment of mesothelioma in particular, we have not discussed at length about the Peritoneal Mesothelioma. Let’s start.
Peritoneal mesothelioma is a very rare cancer. It is also less prevalent as compared to pleural mesothelioma. It occurs in 30% of all mesothelioma cases. The annual incidence varies from 300 to 500 in US. After asbestos exposure, the latency period that elapses until occurrence of symptoms is 20 to 30 years, which is less as compared to pleural mesothelioma. It is believed to be an aggressive form of mesothelioma in all varieties. Though aggressive, it is postulated that the mortality rate is lesser as compared to pleural variety, that is, death is prolonged.
What happens in this malignant mesothelioma?
Peritoneum is a lining that sheaths the abdominal organs. The cells in this lining secrete a fluid that helps the organs to move against each other without friction as while passage of food through intestines. It is made up of two parts, visceral layer and parietal layer. The visceral layer sheaths the internal organs and parietal layer covers the abdominal cavity. The cancer causes these cells to overproduce the fluid. This leads to an excess fluid in the abdominal cavity.
What are the probable causes?
Though the well-known asbestos exposure is the prime cause of concern, it is also stated that, the peritoneal mesothelioma is usually a metastatic variety of pleural cancer. It is usually the result of spread of cancer from lungs to abdomen. It is propounded that the asbestos fibers may be inhaled and then through the draining lymph nodes, it may be disseminated to the abdomen. It is also possible that the asbestos fibers are ingested and resulted in peritoneal cancer.
What are the presenting symptoms of peritoneal mesothelioma?
1) It is observed that these patients usually present with large volume of Ascites, that’s increase in the girth of abdomen because of fluid accumulation.
2) There may be abdominal pain or a palpable mass.
3) There can be constitutional symptoms like fever, weight loss, nausea, anemia or digestive disturbances, etc. associated with the cancer.
4) Many a times, the diagnosis of peritoneal mesothelioma is an accidental finding. The patient usually presents with some other symptom like pelvic pain, gall bladder pain, hernia or just plain gastric disturbance.
5) Some patients complain of vague, non-specific symptoms for a number of months prior to diagnosis of cancer is done.
How to diagnose the condition?
There are two types of malignant mesothelioma affecting abdominal peritoneum.
1) Dry- in this type, CT scan reveals multiple small masses or a single dominant mass that is localized. Ascites is usually very minimal or even absent.
2) Wet- in this type, CT scan may reveal scattered small nodules but there is never a single localized mass. Ascites is usually present.
If the fluid is in excess, it may be removed by a procedure called paracentesis. But the fluid analysis cannot be considered as definitive for the diagnosis of malignant mesothelioma.
The definite diagnosis can only be obtained by biopsy of the tissue done during laparoscopic exploratory.
Staging and Treatment of the peritoneal mesothelioma
Today, no exact staging technique is available for peritoneal mesothelioma. For the treatment purpose, staging is done as per the norms of staging of any cancer. It is called TNM staging (T- tumor, N-lymph nodes, M- metastasis). So, the first stage is a completely localized cancer that can be controlled wholly. The second stage includes a cancer in the abdominal cavity, on the organ surfaces. Here cytoreduction also called as debulking is carried out in which surgeons remove as much visible tumor as possible though not all.
For many patients, surgeons and physicians opt for a multi-modal therapy as a single therapy like surgery has proven ineffective. Usually depending on physician’s consultation, the surgeons combine the cytoreductive surgery with IPHC (Intra-peritoneal hyperthermic chemotherapy) and /or radiation. Also, depending on the response of the patient, systemic chemotherapy with pemetrexed and cisplatin is performed. But the earlier combination of debulking and IPHC has propagated the malignant cancer treatment in a better direction.