Treatment of Pleural Mesothelioma

Oncologists use the three traditional modalities of cancer treatment – surgery, chemotherapy, and radiation – in the treatment of pleural mesothelioma. Doctors determine a treatment regimen for any particular patient by taking into account the stage of the disease, age of the patient, and other health problems the patient has.


Surgery and Chemotherapy

Cytoreduction” or “debulking” are terms used to describe the removal of much, but not all, of the malignant mass. This is sometimes the best the doctor can do because the diffuse nature of the tumor growth. Surgery can take a good portion of the tumorous tissue out. This can help the patient feel better – it reduces pain and makes breathing easier. It might also slow the progression of the cancer in a small measure, but doctors usually understand that surgery cannot fully remove the cancer tissue in the case of mesothelioma.

Prior to any surgery the patient undergoes evaluative procedures to judge fitness for surgery. These include a cardiac stress test and a pulmonary function test. The doctor may order a pulmonary ventilation/perfusion scan, which involves putting radioactive tracers in the body to test lung function. Also known as quantitative V/Q scans, these are commonly done before lung surgery, too. They help the doctors understand which areas of the lungs are working best, and can help guide the surgeon in determining which parts to resect.

Pleurectomy/Decortication involves removal of parietal pleura. The parietal pleura that cors the mediastinum, pericardium, and diaphragm is removed through a thoracotomy. Sometimes part of the diagphragm is removed also. Fewer than 5% of patients die during this form of surgery, which is better than the rate for extrapleural pneumonectomy. This can be a “lung sparing” procedure, which is good for the patient’s general health. It often results in air leakage in the pulmonary system after surgery and empyema.

Extrapleural pneumonectomy requires the surgeon to remove the parterial and visceral pleua with one of the lungs (or section of a lung) and possibly sections of the lymph nodes, diaphragm, and pericardium. It’s a radical surgery.

Chemotherapy for mesothelioma has improved in the past decade with the introduction of the antifolate agent pemetrexed, marketed as Alimta. Studies have shown that a combination regimen of pemetrexed with the alkylating agent cisplatin result in a better response rate than the use of either one by itself. The pemetrexed/cisplatin combination is the closest thing there is to a standard for treatment of pleural mesothelioma. Oncologists may choose other combinations or forgo chemotherapy altogether if they feel that is in the best interest of the patient. More on the timeliness of giving chemotherapy.


Radiation

Pleural mesothelioma unfortunately resists traditional radiotherapy, and brachyotherapy has been tried because the difficult shape of the tumor makes it hard to direct radiation to the affected area. The tumor grows as a diffuse sheet throughout the pleural cavity and radiation would damage healthy lung tissue. Intensity-modulated radiotherapy is used in conjunction with radical resection with extrapleural pneumonectomy.


New Approaches

Despite ongoing research and new treatments available, the prognosis for pleural mesothelioma remains poor. The median survival rate for this cancer is more often measured in months than in years. Current standard treatment for pleural mesothelioma is chemotherapy, sometimes combined with radiation and surgery. Conventional treatment has not appreciably extended life for most patients and, in some cases, has caused more suffering or death. The results of 17 chemotherapy trials for mesothelioma done between 1999 to 2008 showed a survival rate ranging from 6 months to 26.8 months and treatment toxicity ranging from debilitating to fatal.1 An article in The Lancet concluded that chemotherapy for pleural mesothelioma does not significantly increase survival or give patients a better quality of life.2 Surgery often involves removal of a lung and recovery time could be up to a year. Some researchers believe that neither radiation nor surgery benefits patients in terms of survival.3 Despite these grim statistics, researchers are working on promising new treatments. Three novel treatments discussed in this article are chemoembolization, gene therapy, and talc pleurodesis.

Chemoembolization

Dr. Thomas J. Vogl of Frankfurt, Germany is currently conducting a 5-year clinical trial testing chemoembolization. This method involves injecting concentrated cytotoxic drugs directly into the tumors to destroy them. The purpose of the study is to enhance tumor destruction, relieve respiratory symptoms, and prolong life while avoiding the dangerous and sometimes lethal side effects of systemic chemotherapy. One of his patients, a young woman from the United Kingdom, is currently in remission, with an 83% reduction in her tumor since she started treatment in May 2008. Here in the United States, Dr. Robert Taub is conducting a study using a form chemoembolization, with radiation and systemic chemotherapy, at Herbert Irving Comprehensive Cancer Center of the Columbia University Medical Center in New York.4

Gene Therapy

Oncolytic virotherapy, commonly known as “gene therapy”, may be another ray of hope for mesothelioma patients. This treatment involves use of genetically modified viruses that destroy tumor cells without harming adjacent tissue or infecting the patient. An animal study published in The Journal of Gene Medicine (May 2006) included some rather impressive results. Mice previously infected with pleural mesothelioma were either treated with herpes simplex virus NV1066 or injected with a saline solution (PBS). The median survival times are as follows: Those treated early in their disease with a single dose of NV1066 lived 95 days, whereas the PBS-treated mice lived only 19 days. The group given three doses NV1066 injected into the pleura survived 86 days and the ones given PBS lived for 21 days. The mice treated systemically with NV1066 lived 89 days and their PBS-treated cohorts lasted only 23 days.5 Considering the average life span of a mouse in captivity is about two years, 95 days represents 13% of its total life. In human terms (assuming an average life span of 78 years), this would mean 10 more years. However, research of gene therapy for cancer is in its early stages and this kind of success has yet to be been replicated in human subjects.

Talc Pleurodesis

A surprising treatment for pleural mesothelioma uses talc, a common and inexpensive mineral. The journal Respirology reported in November 2005 that talc was used to treat mesothelioma patients with pleural effusions (fluid between the pleural membranes). Not only did these 26 patients live longer (median survival 19.4 months), they were able to breath better after talc poudrage. No deaths resulted from this treatment and the hospital stay was only a few days. Based on these findings, authors of this study recommended further research.6 More on treatment of pleural effusions.

The University of Florida routinely performs talc pleurodesis on lung cancer patients to alleviate shortness of breath. One professor, Dr. Veena Antony, noted that patients who underwent the talc treatment lived about a year and one-half longer than usual. Dr. Antony’s research revealed that talc prevented tumors from creating blood vessels, causing them to shrink and sometimes disappear completely. The talc also causes normal healthy cells to quickly start producing endostatin, a hormone that destroys tumors.7

Information about current clinical trials can be found online at http://www.cancer.gov/search/SearchClinicalTrials.aspx. Or contact us here at Mesothelioma Aid for help.

1 Cancer Monthly [Search Results for Mesothelioma treated with chemotherapy in U.S.],. http://www.cancermonthly.com/SearchResults.asp?fld_PreferredTreatment=false&fld_TreatmentLocations=0&SubTypeCancer=57&PreferredTreatment=2&TreatmentLocations=1&Submit2=Search, Accessed 20 June 2009

2 Daniel Morgensztern, "Thymoma and Mesothelioma, " The Washington Manual of Oncology,”. Ramaswamy Govindan, Second Edition, Lippincott Williams & Wilkins, 1 Oct. 2007, 178, http://books.google.com/books?id=U4di7rRgYQoC&pg=PA177&lpg=PA177&dq=mesothelioma+radiation+survival&source=bl&ots=STlM7_Mt_U&sig=SPlVV9eMZP-Nw3d1ov9_72qEcB0&hl=en&ei=HMFCStS8GaOqtgevnvHcAg&sa=X&oi=book_result&ct=result&resnum=6, Accessed 20 June 2009.

3 Martin F. Muers, et al, 2008, “Active symptom control with or without chemotherapy in the treatment of patients with malignant pleural mesothelioma (MS01): a multicentre randomised trial, ”The Lancet, Volume 371, Issue 9625, 1685 - 1694, 17 May 2008, http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(08)60727-8/fulltext, Accessed 19 June 2009.

4 Medical News Today. 2008, New Clinical Trial For Patients With Asbestos-Associated Lung Cancer, http://www.medicalnewstoday.com/articles/112933.php, Accessed 19 June 2009

5 Prasad S. Adusumilli, et al, 2006, “Imaging and Therapy of Malignant Pleural Mesothelioma using Replication-competent Herpes Simplex Viruses,” The Journal of Gene Medicine, Volume 8, Issue 5, 603 - 615, 13 February 2006, <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1804293>, Accessed 20 June 2009.

6 Yossef Aelony and Janis Yao, 2005, “Prolonged survival after talc poudrage for malignant pleural mesothelioma: Case series,” Respirology, Volume 10, Number 5, 649-655(7), November 2005, <http://www.ingentaconnect.com/content/bsc/res/2005/00000010/00000005/art00016>, Accessed 19 June 2009.

7 University of Florida, “Talcum powder stunts growth of lung tumors,” University of Florida Shands Cancer Center, June 6, 2007, http://www.ufscc.ufl.edu/Patient/content.aspx?section=ufscc&id=39928, Accessed 19 June 2009.

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