How Do People Get Mesothelioma?

Because mesothelioma is so rare, the cancer was misdiagnosed for decades. It wasn’t until the 1960s that doctors started to research mesothelioma and its connection to asbestos in depth.

Researchers still have plenty to learn about mesothelioma, which accounts for less than 0.3% of all cancer diagnoses in the United States. While the primary cause of mesothelioma is undeniable — asbestos exposure is the leading cause — other aspects of this cancer remain a challenge for the medical community.

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. Researchers have yet to perfect early diagnosis techniques, so mesothelioma is typically diagnosed in the later stages or progression when it is more difficult to treat.

This cancer is still considered incurable, although advances in treatment allow patients to live longer, better-quality lives. Only about 15% to 20% of people with pleural mesothelioma, which is the most common type, qualify for surgeries that help some people live years longer than the average one-year prognosis.

Doctors, researchers and advocacy groups continue to raise funds for research and awareness about mesothelioma in hope to one day find a cure.

When Was Mesothelioma First Discovered?

The term “mesothelioma” was first used in the early 1900s to describe this cancer, but tumors in the mesothelium were initially identified in the mid-1700s. This cancer is called mesothelioma because it forms in the mesothelium, which is a protective layer that surrounds internal organs.

  • 1767
    Joseph Lieutaud, the founder of pathologic anatomy in France, made the earliest mention of a tumor in the pleural mesothelium (lining of the lungs). In a publication detailing the study of approximately 3,000 autopsies he performed, Lieutaud mentioned two cases of “pleural tumors,” possibly the first recorded cases of pleural mesothelioma.
  • 1819
    René-Théophile-Hyacinthe Laennec, the French physician who invented the stethoscope, suggested malignancy could arise from the pleura, based on his understanding of the nature of pleural cells.
  • 1843
    Karl Freiherr von Rokitansky, professor of pathological anatomy at Vienna University, challenged that notion. He stated pleural cancer was always secondary to a primary cancer elsewhere in the body. Regardless of the lack of compelling evidence, this became the accepted theory of the medical establishment for many years. Ironically, von Rokitansky described primary tumors of the peritoneum in 1954, likely the first recorded cases of peritoneal mesothelioma.
  • Early 1900s
    The medical community began to finally accept that cancers could originate in the pleura without having spread from a primary cancer elsewhere in the body.
  • 1909
    J.G. Adami coined the term “mesothelioma” to classify this rare cancer.
  • 1935
    Steven R. Gloyne, a British pathologist, was the first to suggest that mesothelioma was caused by occupational asbestos exposure.
  • 1943
    H.W. Wedler, a German researcher, published a study of asbestos workers showing a connection between asbestosis and pleural mesothelioma.
  • 1960
    J. Christopher Wagner published a study of 33 mesothelioma cases linked to an asbestos mine in South Africa, which confirmed the causal relationship beyond reasonable doubt.

In the decades that followed, scientific research continued to establish evidence linking mesothelioma to asbestos exposure, and workers began filing lawsuits against asbestos manufacturers.

Historical Studies of Mesothelioma and Asbestos Exposure

After many years of research, conjecture and controversy, most of the world’s medical establishment accepted two important facts about mesothelioma:

  • The disease was a distinct diagnostic entity.
  • The association between mesothelioma and asbestos exposure had been proven conclusively.

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

Perhaps the most important study that documented the unmistakable connection between asbestos exposure and cancer was presented by medical researcher J.C. Wagner and physician Chris Sleggs.

In their paper published by the British Journal of Medicine in 1960, Sleggs and Wagner detailed 33 cases of mesothelioma they discovered in residents of South Africa’s northwest Cape Province where crocidolite asbestos was mined.

In eight cases, the asbestos exposure history was occupational. The rest of the patients had lived near the mines for most of their lives.

American Study

American physician Dr. Irving J. Selikoff presented his research at the 1964 Biological Effects of Asbestos conference, sponsored by the New York Academy of Science.

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 would be expected statistically. The deceased workers had died from a variety of diseases, including asbestosis, asbestos-related lung cancer and other types of lung, stomach and colorectal cancers.

British Study

Another study by British physician Molly Newhouse found mesothelioma cases among people who lived near, but were not employed by, a London asbestos factory.

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.

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Environmental Studies

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 with asbestos mines, cement plants, shipyards, textile or brake factories. It found that living within 2000 meters of these locations was associated with a high risk of mesothelioma. 

A 2017 review of environmental asbestos exposure and the risk of mesothelioma concluded that occupational exposure remains the No. 1 cause of this rare cancer. The study authors 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. However, more precise surgical procedures, improved chemotherapy regimens and emerging treatments such as immunotherapy are helping patients survive longer than ever before.

Cutting-edge clinical trials are currently testing these treatments and others in search of a mesothelioma cure. Researchers are also investigating ways to improve the diagnosis of mesothelioma, which 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.

In the 1960s, the pleurectomy and decortication procedure was introduced, a mesothelioma surgery that is still widely used today. It was originally used on patients with trapped lung caused by tuberculous empyema.

In the 1970s, doctors experimented with another surgery called an extrapleural pneumonectomy, which was also originally used to treat tuberculous empyema. 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, was developed in the 1990s, and Dr. Paul Sugarbaker was among the first to use it on peritoneal mesothelioma patients. In combination with cytoreductive surgery, HIPEC helps half of peritoneal mesothelioma patients who receive the procedure live longer than five years.

Advancements in Chemotherapy

A number of chemotherapy drugs were used to treat mesothelioma from the 1970s through the 1990s, such as doxorubicin and cisplatin, with response rates between 20% and 40%.

In 2003, the phase III trial of cisplatin and pemetrexed (Alimta) for mesothelioma reported the best chemotherapy response rate to date of 41.3%.

After that study, the U.S. Food and Drug Administration added cisplatin and pemetrexed 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 that was typically combined with surgery. Some patients have received heated chemotherapy without surgery, but it is typically administered following surgery. 

Advancements in Radiation Therapy

Doctors began experimenting with radiation therapy for mesothelioma in the 1950s using intrapleural instillation of radioactive colloidal gold. For decades, it was believed radiation therapy was too difficult to deliver to the lung lining without harming other vital organs such as the heart.

A 2001 phase II clinical trial changed that perspective when it reported a low 13% local recurrence rate when radiation therapy was applied after extrapleural pneumonectomy surgery. Advanced techniques are used today to reduce radiation exposure to vital organs, such as intensity-modulated radiation therapy.

A relatively new type of radiation called proton therapy uses a beam of protons instead of photons to better target 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

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.

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