There is always research going on in the area of mesothelioma. Scientists are looking for causes and ways to prevent mesothelioma. Doctors are working to improve accuracy of diagnosis and effectiveness of treatment. Despite recent progress, much remains to be learned about the best way to treat these cancers.

Causes and prevention

Much of the research on mesothelioma has focused on learning exactly how asbestos changes mesothelial cells and their DNA to cause these cancers. Understanding how these fibers produce cancer might help us develop ways to prevent those changes.

The role of asbestos in increasing the risk of mesothelioma is a definite public health concern. Researchers are continuously learning more about which fibers can produce cancer, how they cause these cancers, and what levels of exposure can be considered safe. Now that the dangers of asbestos are known, we can limit or stop exposure in homes, public buildings, and the workplace. Unfortunately, regulations protecting workers from asbestos exposure are much less stringent in some countries than in others.

Research is also under way to clarify the role (if any) of SV40, a virus that has been linked to mesothelioma in some studies.

Treatment

Mesothelioma remains a difficult cancer to treat, and doctors are constantly trying to improve on current approaches. The roles of surgery, radiation therapy, and chemotherapy in the treatment of mesothelioma are highly debated. Treatments that use some combination of surgery, radiation therapy, and chemotherapy, called multimodality therapy, are now being studied and may provide the most promising option for some patients.

Radiation therapy

Mesothelioma does not usually grow as a well-defined tumor. This makes it difficult to aim radiation at it without affecting nearby healthy tissues, which has limited the use of radiation therapy against this cancer.

Newer radiation therapy techniques, such as three-dimensional conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) use computers to more precisely map tumors and to deliver radiation more accurately. This may limit side effects and allow doctors to use higher dose of radiation on the tumors themselves.

Chemotherapy

Some chemotherapy drugs can shrink or slow the growth of mesotheliomas, but in most cases the effects last for a limited time. Several newer chemotherapy drugs, including raltitrexed, are currently being tested in clinical trials, together with other types of treatment.

As mentioned in the section "How is malignant mesothelioma treated?", doctors are now studying giving chemotherapy drugs directly into the chest or abdominal cavity, often right after surgery. In some cases the drugs are heated before giving them, which may make them work better. Doctors hope that putting the drugs directly into contact with the tumors may allow them to work better, while limiting the side effects in the rest of the body.

Photodynamic therapy

Another technique now being studied is photodynamic therapy (PDT). For this treatment, a light-activated drug is injected into a vein. The drug spreads throughout the body and tends to collect in cancer cells. A few days later (usually just after surgery for the mesothelioma), a special red light on the end of a tube is placed into the chest cavity. The light causes a chemical change that activates the drug and causes the cancer cells to die. Since the drug is only active in the areas exposed to the special light, this approach may cause fewer side effects than use of drugs that spread throughout all tissues of the body. Several clinical trials are now studying the use of PDT for mesothelioma.

Targeted drugs

In general, chemotherapy drugs are limited in their effectiveness against advanced mesothelioma. As researchers have learned more about the changes in cells that cause cancer, they have been able develop newer drugs that specifically target these changes. Targeted drugs work differently from standard chemotherapy drugs. They often have different (and less severe) side effects.

One group of targeted drugs is known as angiogenesis inhibitors. These drugs target the growth of new blood vessels (angiogenesis), which tumors need to grow larger. Some of these drugs are already used to treat other types of cancer and are now being studied for use against mesotheliomas. Examples of these drugs include bevacizumab (Avastin) and sorafenib (Nexavar).

Other new drugs have different targets. For example, ranpirnase (Onconase) is an enzyme that breaks down RNA (part of a cell's genetic material) and causes cancer cells to die at the right time. In early studies it has helped some patients with mesothelioma to live longer. Larger clinical trials are currently in progress.

Other new targeted drugs being tested in mesothelioma clinical trials include imatinib (Gleevec), erlotinib (Tarceva), dasatinib (Sprycel), bortezomib (Velcade), sunitinib (Sutent), and vorinostat (Zolinza).

Gene therapy

A newer type of treatment being tested on mesothelioma is gene therapy, which attempts to replace or repair defective genes in cancer cells. One approach to gene therapy uses special viruses that have been modified in the lab. The virus is injected into the pleural space and infects the mesothelioma cells. When this infection occurs, the virus injects the desired gene into the cells. Research on gene therapy is still in the early stages.

Last Medical Review: 03/17/2009
Last Revised: 03/17/2009