Mesothelioma is a cancer unique to people who have been exposed to asbestos. In fact, asbestos exposure is the only known cause of mesothelioma in the United States. Approximately 80% of mesothelioma cases appear in people who are known to have been exposed to asbestos in the workplace, from personal use such as home repairs or automotive work, from second–hand exposure to a family member’s work clothes or the environment. The remaining 20% of people diagnosed with mesothelioma are usually not able to determine how, when or where they were exposed to asbestos. Being a rare form of cancer, only about 3,000 new cases of mesothelioma are diagnosed every year. Because it takes 20 to 60 years to develop mesothelioma after first exposure to asbestos, many people are over the age of 65 when diagnosed. However, younger people are not immune from mesothelioma. The risk of developing mesothelioma for people exposed to asbestos remains throughout their lifetime.
Types of Mesothelioma
There are four types of mesothelioma, occurring in different parts of the body: pleural mesothelioma (chest), peritoneal mesothelioma (abdomen), pericardial mesothelioma (heart) and testicular mesothelioma (testicle).
Pleural mesothelioma is the most common form of mesothelioma. The pleura is a membrane that lines the thorax (chest cavity) inside the rib cage. When inhaled, asbestos fibers can pierce this membrane and become lodged in the pleura causing inflamation, scarring and cancer. A diagnosis of pleural mesothelioma may not appear for 20 to 60 years after first exposure to asbestos. Likewise, symptoms may not appear until soon before or after the diagnosis. Symptoms may include chest pain, shortness of breath, back and shoulder pain, fever, sweating, fatigue, weight loss, trouble swallowing, hoarseness, muscle weakness and persistent cough.
The peritoneum is the membrane that surrounds the internal organs of the abdomen. Cancer of the peritoneum caused by asbestos exposure is known as peritoneal mesothelioma. Carcinogenic asbestos fibers are inhaled or ingested and become trapped in the abdominal lining causing cancer. The cancer usually grows slowly and can take decades before it is able to be diagnosed or symptoms develop. Symptoms include nausea, vomiting, fatigue, weight loss, abdominal bloating and fever. Sometimes a growing tumor puts pressure on internal organs and causes extreme abdominal pain.
Pericardial mesothelioma is extremely rare, accounting for approximately 5 percent of all mesothelioma cases. Pericardial mesothelioma attacks the membrane lining the heart. Asbestos particles travel from the lungs to the mesothelial tissue that surrounds the heart where they lodge and cause cancerous tumors to form. As the tumors grow, they can restrict heart function and cause cardiac problems, including heart failure. Symptoms of pericardial mesothelioma include irregular heart beat, chest pain, loss of appetite, hypertension and fatigue.
Testicular mesothelioma is the rarest form of mesothelioma, with less than 100 documented cases worldwide. The disease attacks the tunica vaginalis, the thin membrane that surrounds and protects the testicles within the scrotum. Some clinically reported symptoms have included lumps and swelling.
Mesothelioma Symptoms And Diagnosis
Mesothelioma has the longest latency period of all asbestos diseases. It can take anywhere from 20 to 60 years from first exposure to asbestos until a diagnosis is made. Symptoms which may appear in later stages are chest, back and shoulder pain, shortness of breath, cough, weight loss, fatigue, pleural effusion and other symptoms which may be related to metastases or pressure on adjacent organs.
To make or confirm a diagnosis of mesothelioma and to help choose a treatment regimen, doctors use tests called cytology and biopsy to determine what kind(s) of cancer cells are present in the body. Cytology examines the cancer cells in a fluid sample; biopsy examines cancer cells in a tissue sample.
Treatments for Mesothelioma
Treatments are chosen based on an individual’s goals, overall health and the stage and location of the mesothelioma. Mesothelioma is often diagnosed at an advanced stage, when complete surgical removal of the tumor is no longer an option. Some combination of surgery, chemotherapy and radiation may be used to slow the progression of disease and/or reduce discomfort and symptoms. In many cases, people opt for treatments that can manage their symptoms and help them remain as comfortable as possible.
Treatment options for mesothelioma include:
It is possible to surgically remove a mesothelioma tumor if it is discovered at an early stage. Otherwise, depending on the location and cell type of the tumor, doctors may recommend surgery to alleviate symptoms and focus on improving the quality of life. For example, surgery can be used to:
– Reduce fluid build-up: in cases of pleural mesothelioma, doctors sometimes alleviate breathing problems by draining excess fluid from the chest (pleurodesis) and injecting medicine into the chest cavity to prevent excess fluid from returning (talc pleurodesis).
– Relieve pain and discomfort: doctors may recommend removing as much tumor as possible, or removing the affected areas in order to alleviate symptoms.
Chemotherapy may be used either systemically (throughout the body) or directly into the site of the mesothelioma to kill cancer cells. It also may be used before surgery (neoadjuvant chemotherapy) or after surgery (adjuvant chemotherapy) to improve outcomes and prevent cancer cells from recurring.
Radiation therapy focuses on exact targets to kill cancer cells and can sometimes alleviate symptoms such as pain and shortness of breath from mesothelioma. Radiation may also be used to prevent mesothelioma cells from invading the site of a biopsy or other surgical site.
Combination therapy refers to any treatment regimen that has been customized for an individual’s needs and involves some combination of surgery, chemotherapy, and/or radiation.
Doctors should be able to direct patients to clinical trial that might be appropriate for them. Clinical trials present an opportunity to receive the most recent, emerging therapies to treat mesothelioma. Participaton in this research can help mesothelioma sufferers presently and in the future.
Some clinical trials are studying the safety and effectiveness of targeted drugs to kill mesothelioma cells by exploiting their specific abnormalities. Other therapies under clinical investigation include interleukin-2 (a biologic therapy), lovastatin (a cholesterol-lowering drug), immunotherapy, gene therapy, and photodynamic therapy.
The Benjamin Shein Family Foundation is proud to have supported a 2011 clinical study at Perelman School of Medicine at the University of Pennsylvania that showed promise for using immuno-gene therapy to treat early stage mesothelioma. The approach modified a cold virus to express high levels of a powerful immune system stimulant called interferon-alpha. The modified virus is administered to stimulate the body’s own immune response, producing anitbodies to potentially attack the tumor. Penn Medicine’s researchers continue to study this new form of immuno-gene therapy as an adjunct to chemotherapy in treating mesothelioma.
Although none have been shown to cure mesothelioma, alternative therapies may help reduce the pain and discomfort of mesothelioma symptoms. For example, in addition to oxygen and medication prescribed by a doctor, acupuncture, breath training and relaxation exercises may help relieve feelings of breathlessness.
The Three Types of Mesothelioma Cancer Cells
There are three types of mesothelioma cell types. They are:
Epithelioid Mesothelioma Cells
Epithelioid (or epithelial) mesothelioma cells are the most common type of mesothelioma cancer cells, found in 50 to 70 percent of all cases. Epithelioid cells appear in a tubular pattern of cube or box-like shapes. Each cell has a clearly defined nucleus. Epithelioid mesothelioma cells closely resemble other types of cancer cells so a pathologist must carefully examine them to ensure a correct diagnosis.
Sarcomatoid Mesothelioma Cells
Sarcomatoid mesothelioma cells are found in 10 to 15 percent of cases. These cells form irregular patterns and are generally oval in shape. The nucleus is not as clearly defined as in epithelioid cells. Sarcomatoid mesothelioma cells resemble cells of sarcomatoid carcinoma and other sarcoma cancers. Careful examination by a pathologist is necessary to ensure a correct diagnosis.
Biphasic Mesothelioma Cells
About 45 to 65 percent of mesothelioma cases are diagnosed as biphasic mesothelioma, meaning that both epithelioid and sarcomatoid mesothelioma cancer cells are present. Biphasic mesothelioma cells differ from the first two types because there is not one unique cellular pattern. Cells can appear mixed together or separately.