The nature of mesothelioma tumors isn’t like other cancers. They develop in a unique way that helps explain the difficulty in treating the disease.
Tumors of the Pleura and Peritoneum
Mesothelioma tumors aren’t like tumors that form in other cancers. The production of mesothelioma in the lining of the chest and abdomen creates difficulties in treatment. This is related to the relatively short prognosis of mesothelioma patients, but specialists are constantly developing new treatments to fight mesothelioma tumors.
Attributes of Mesothelioma Tumors
These tumors develop from the healthy mesothelial cells found in the linings of major organs. Asbestos fibers cause genetic mutations in these cells that cause them to replicate uncontrollably, forming a tumor.
Mesothelioma tumors are different than those of other organ cancers because they originate in the lining of the lungs and abdomen. These tumors spread across the surface of the lung or abdominal organs.
Currently, the most effective way to treat mesothelioma tumors is surgery. However, the nature of mesothelioma tumors makes it hard for doctors to completely remove them. It also makes the process more likely to leave microscopic cells behind after surgery.
How Tumors Develop
Mesothelioma develops years after exposure to asbestos. Inhaling or ingesting these microscopic asbestos fibers causes changes in the genetic makeup of healthy mesothelial cells, which make up the lining of the chest and abdomen.
Initially, natural defenses in the body fight these mutated mesothelial cells. The immune system keeps them in check until asbestos fibers lodged in the linings of the chest and abdomen produce more mesothelioma cells than the body’s immune system can fight. Uncontrollable cell growth eventually produces a tumor.
A Consistent Blood Supply
Mesothelioma tumors need a consistent blood supply to flourish. Blood vessels feed tumors with nutrients needed to continue growing. Mesothelioma tumors have the capacity to produce new blood vessels. This process is known as angiogenesis. Without a blood supply, tumors don’t have the essential nutrients to continue growing. Doctors are currently developing drugs to inhibit angiogenesis.
Early Mesothelioma Tumor Development
Signaling Pathways and Growth Factors
When the DNA of healthy mesothelial cells is damaged, so are the signaling pathways that cells use to communicate with each other. These signaling pathways are used by healthy cells to know when to stop multiplying and finally undergo apoptosis (programmed cell death). There are two signaling pathways that have been identified as playing a large part in mesothelioma tumor growth. These are:
Epidermal Growth Factor Receptor (EGFR)
This receptor is naturally present on the surface of many healthy cells; however, it is overabundant in mesothelioma. EGFR allows mesothelioma tumors to grow and become more aggressive.
Vascular Endothelial Growth Factor (VEGF)
VEGF refers to a group of proteins present in cancer cells that are essential to the growth of blood vessels. Mesothelioma cells produce VEGF to stimulate the growth of tumors.
Acceptable Margins and Limits in Surgery
The goal of surgery is to gain what is called an acceptable margin. The margin itself includes the removal of the entire tumor and any surrounding tissue that may harvest microscopic cancer cells. By removing enough of the extra tissue surrounding a tumor, in addition to the tumor itself, doctors hope to decrease the likelihood for more tumor growth in that area. The seemingly tumor-free extra tissue is then tested for cancer cells. If this comes back clean, they are said to have achieved an acceptable margin.
Acceptable margins may be easier to obtain for tumors found in diseases like breast cancer. These tumors are surrounded by fatty tissue. It is much harder to gain an acceptable margin in cancers of the lung, and the nature of mesothelioma tumors makes this even harder.
Mesothelioma is sometimes referred to as “diffuse malignant mesothelioma” because the tumors are small and dispersed over the surface lining of the lungs or abdomen. While many tumors start inside of organs, these start on the surface and spread to other nearby organs and tissue.
There are three surgeries for mesothelioma:
- Extrapleural pneumonectomy (EPP) for pleural mesothelioma
- Pleurectomy/decortication (P/D) also for pleural mesothelioma
- Cytoreduction with HIPEC for peritoneal mesothelioma
In the treatment of most cancers, the notion of “acceptable margins” has become the goal of surgery. Acceptable surgical margins are hard, and only theoretically possible, to acquire in mesothelioma patients.
A Note on the Pleural Mesothelioma Surgical Debate
The extrapleural pneumonectomy is designed to remove as much of the cancerous region as possible. This includes the infected lining of the lungs and chest cavity as well as the lung itself. The goal of this procedure is to gain an acceptable margin. Those who support the alternative pleurectomy/decortication, a lung-sparing procedure, generally don’t think an acceptable margin is possible.
The type of procedure best for you depends on your specific diagnosis. The success of either procedure also heavily depends on the experience of the surgeon. Find a mesothelioma specialist to discuss your surgical options today.
Moving Beyond Surgery
Surgery remains one of the best options for mesothelioma patients to improve their life expectancy. However, this is typically only an option for early stage patients with small, localized tumors. Patients with in the more advanced stages of mesothelioma are unlikely to benefit from having surgery.
There are many other options for treating mesothelioma in all stages. Traditional treatment methods, such as chemotherapy, remain a standard option for most patients. However, as new treatment methods develop, doctors are moving toward a model of managing mesothelioma like a chronic disease.
Novel treatments that stop the growth of mesothelioma tumors, but don’t necessarily kill mesothelioma cells, can increase survival time. These treatments are developing out of the realization that cancer patients can live years with a tumor.
This is being accomplished by developing drugs that:
- Cut off the blood supply to tumors
- Interrupt signaling between tumor growth receptors
- Use the immune system to attack tumors
These novel treatments are mostly available as clinical trials. Some of these trial drugs are proving to have serious potential based on their early phase trials. Get connected to recruiting clinical trials for mesothelioma today.
In rare cases, patients are diagnosed with benign mesothelioma. Benign tumors are non-cancerous. These tumors can be removed surgically with little or no other treatment. Benign mesothelioma is not deadly and does not usually spread to other organs.
There are four main types of benign mesothelioma:
- Benign cystic mesothelioma
- Well-differentiated papillary mesothelioma
- Benign adenomatoid tumors
- Localized fibrous tumor of the pleura
Most cases of mesothelioma are malignant. Malignant mesothelioma tumors are cancerous and more difficult to treat than benign tumors.