How Do People Get Mesothelioma?
Mesothelioma carries a long latency period. It can take anywhere from 15 to 70 years for the cancer to develop after a person’s first exposure to asbestos.
This cancer is still considered incurable. Advances in treatment allow patients to live longer, better-quality lives. Only about 15% to 20% of people with pleural mesothelioma qualify for surgery. Surgeries help some people live years longer than the average one-year prognosis.
Doctors, researchers and advocacy groups hope to one day find a cure.
When Was Mesothelioma First Discovered?
Tumors in the mesothelium were first identified in the mid-1700s. The term “mesothelioma” was first used in the early 1900s. It forms in the mesothelium, a protective layer that surrounds internal organs.
Joseph Lieutaud is the founder of pathologic anatomy in France. He made the earliest mention of a tumor in the pleural mesothelium (lining of the lungs). Lieutaud documented the first recorded cases of pleural mesothelioma.
René-Théophile-Hyacinthe Laennec is the French physician who invented the stethoscope. He suggested malignancy could arise from the pleura.
Karl Freiherr von Rokitansky was a professor of pathological anatomy at Vienna University. He challenged that notion. He stated pleural cancer was always secondary to a primary cancer elsewhere in the body. This became the accepted theory of the medical establishment for many years. He described primary tumors of the peritoneum in 1954. It was among the first recorded cases of peritoneal mesothelioma.
The medical community began to accept that cancers could originate in the pleura.
J.G. Adami coined the term “mesothelioma” to classify this rare cancer.
Steven R. Gloyne was a British pathologist. He was the first to suggest that occupational asbestos exposure causes mesothelioma.
H.W. Wedler was a German researcher. He published a study of asbestos workers. It showed a connection between asbestosis and pleural mesothelioma.
J. Christopher Wagner published a study of 33 mesothelioma cases linked to an asbestos mine in South Africa. It confirmed the causal relationship beyond a reasonable doubt.
Scientific research continued to establish evidence linking mesothelioma to asbestos exposure. Workers began filing asbestos lawsuits in the 1920s. By the end of the 1970s, mesothelioma lawsuits became common.
Historical Studies of Mesothelioma and Asbestos Exposure
The medical establishment has accepted two important facts about mesothelioma:
- The disease is a distinct diagnostic entity.
- The association between mesothelioma and asbestos exposure is proven.
Groundbreaking German Study
In 1943, H.W. Wedler was the first to report a connection between asbestosis and cancer of the pleura among German asbestos workers. Approximately 20% of the workers developed cancer, with lung cancer more common than mesothelioma.
Wedler’s study was well received in Germany. But the political climate at the time caused the rest of the world to ignore research coming from Nazi Germany.
South African Study
J.C. Wagner and physician Chris Sleggs led a study on asbestos exposure. It showed a connection between asbestos exposure and cancer.
In their paper published by the British Journal of Medicine in 1960. It detailed 33 cases of mesothelioma they discovered in residents of South Africa. Crocidolite asbestos mining contaminated the area around the mine.
In eight cases, the asbestos exposure history was occupational. The rest of the patients had lived near the mines for most of their lives.
A Biological Effects of Asbestos conference took place in 1964. American physician Dr. Irving J. Selikoff presented research at the conference.
For more than a year, Selikoff had examined more than 1,000 workers from the Union Asbestos & Rubber Company plant in Patterson, New Jersey.
Selikoff found the mortality rate among these employees was 25% higher than expected. The deceased workers died from asbestosis and asbestos-related lung cancer. As well as other types of lung, stomach and colorectal cancers.
Another study found mesothelioma cases among people who lived near a London asbestos factory. British physician Molly Newhouse led the study.
By 1968, the British Medical Journal claimed asbestos was the direct cause of most mesothelioma cases. Controversy still raged as to what types of asbestos were the most carcinogenic — a contentious argument that still echoes to this day.
Research on environmental asbestos exposure as a potential cause of mesothelioma began in earnest in 2000. A study evaluated six communities in Italy, Spain and Switzerland. They had asbestos mines, cement plants, shipyards, textile or brake factories. It found that living within 2000 meters of these locations led to a high risk of mesothelioma.
A 2017 review looked at environmental asbestos exposure and the risk of mesothelioma. It concluded that occupational exposure remains the No. 1 cause of this rare cancer. It reported that consumer contact with legacy and new asbestos products would remain an exposure pathway.
History of Mesothelioma Treatment
Despite decades of research, there still is no definitive cure for the four types of mesothelioma. Better treatments help some patients survive longer than ever before.
Cutting-edge clinical trials look for a mesothelioma cure. Researchers also investigate ways to improve the diagnosis of mesothelioma. It may lead to earlier diagnoses and improved prognosis.
Advancements in Surgery
Surgical treatment of mesothelioma began in the 1940s with the use of pneumonectomy and pleurectomy. Pneumonectomy is also used to treat lung cancer.
A pleurectomy and decortication procedure developed in the 1960s. This mesothelioma surgery is still used today. It first helped patients with trapped lung caused by tuberculous empyema.
In the 1970s, doctors experimented with another surgery called an extrapleural pneumonectomy. The mortality rate for this surgery back then was as high as 31%. Today it’s around 4% in leading cancer centers.
Heated intraperitoneal chemotherapy, or HIPEC, came about in the 1990s. Dr. Paul Sugarbaker was among the first to use it on peritoneal mesothelioma patients. HIPEC surgery helps half of peritoneal mesothelioma patients live longer than five years.
Advancements in Chemotherapy
Several chemotherapy drugs treated mesothelioma from the 1970s through the 1990s. Response rates between 20% and 40% kept doctors searching for more options.
In 2003, the phase III trial of cisplatin and pemetrexed (Alimta) reported the best chemotherapy response rate to date of 41.3%.
The U.S. Food and Drug Administration added the drugs to the standard-of-care treatment for mesothelioma. The drug combination remains the most common mesothelioma treatment.
In the 1990s, heated chemotherapy became an experimental treatment. Some patients have received heated chemotherapy without surgery, but that is not the norm.
Advancements in Radiation Therapy
Doctors began experimenting with radiation therapy for mesothelioma in the 1950s. They used intrapleural instillation of radioactive colloidal gold. For decades, doctors believed radiation was too difficult to deliver to the lung lining. It was too easy to harm other vital organs such as the heart.
A 2001 phase II clinical trial changed that perspective. It reported a low 13% local recurrence with radiation therapy. Application after extrapleural pneumonectomy surgery was key. Advanced techniques used today reduce radiation exposure to vital organs.
A new type of radiation called proton therapy uses a beam of protons instead of photons. It better targets mesothelioma tumors. Proton therapy is only available at certain cancer centers in the U.S.
FDA Approves New Therapies for Mesothelioma
The U.S. Food and Drug Administration approved two new therapies for mesothelioma in 2019 and 2020.
In 2020, the FDA approved the nivolumab (Opdivo) and ipilimumab (Yervoy) combination immunotherapy as a new first-line treatment for mesothelioma. Patients survive an average of 18 months on this new treatment compared to 14 months for first-line chemotherapy. Two-year survival is 41% for immunotherapy patients compared to 27% for chemotherapy patients.
In 2019, the FDA approved Tumor Treating Fields in combination with chemotherapy for mesothelioma. Also known as TTFields, the therapy uses alternating electrical fields to control tumor growth. The addition of TTFields to chemotherapy helps patients live an average of six months longer.
Emerging treatments for mesothelioma are under development in clinical trials throughout the world.
Therapies under investigation for mesothelioma treatment including immunotherapy, vaccine therapy, gene therapy, epigenetic therapy, virotherapy and anti-angiogenic drugs.
Photodynamic therapy, which uses light and photosensitizing drugs to kill cancer cells, is also being tested on mesothelioma. Cryotherapy, which uses freezing temperatures to kill cancer cells, helped relieve chest pain in a 2020 study.
Many of these therapies are available through clinical trials in the U.S.
Future of Mesothelioma Research
The first and only standalone research facility developed to focus on mesothelioma opened in Sydney, Australia, in 2009. The Asbestos Diseases Research Institute conducts research primarily on mesothelioma treatment, including looking for new ways to treat this cancer.
The center also studies the diagnosis of mesothelioma and the psychological impact the cancer has on patients and families.
Certain cancer centers in the U.S. feature programs that focus on the treatment of mesothelioma and participate in clinical trials.
For example, the International Mesothelioma Program at Brigham and Women’s Hospital in Boston is renowned for its surgical expertise and clinical trial leadership. The Pacific Mesothelioma Center in Los Angeles has been researching immunotherapy and gene therapy for mesothelioma since 2002.
The mesothelioma program at the University of Chicago Comprehensive Cancer Center helped develop the only FDA-approved chemotherapy regimen for mesothelioma. The Mesothelioma International Treatment Program at AdventHealth in Celebration, Florida, is known for robotic surgery and clinical research.
Since 1991, the global mesothelioma community has united every two years for the International Mesothelioma Interest Group Meeting at different locations throughout the world. The conference brings together researchers and mesothelioma experts to share developments in treatment and discuss future research towards a cure.