Category: Featured News
Asbestos Exposure Still Experienced by Majority of World’s Population
The use of asbestos has dropped from more than 4 million metric tons to 2.1 million metric tons in the past 25 years as one country after another has banned the cancer-causing mineral fiber. Yet, a majority of the world’s population still lives in countries including the United States that do not ban asbestos or asbestos-containing products. And demand for asbestos is surging in industrializing countries such as China and India where safeguards on worker exposure are weak or non-existent.
Today, the top users of asbestos are China, Russia, India, Kazakhstan and Brazil. These countries export asbestos-containing products to other countries including the U.S. where the products are used in the automotive and construction industries and pose an ongoing threat of asbestos exposure. Asbestos causes about half the of total deaths from workplace-related cancers such as mesothelioma, a cancer of the lining of the lung or abdomen, according to the World Health Organization.
While the U.S. stopped mining asbestos and producing asbestos in 2002, according to a recent article in Environmental Health Perspectives, a peer-reviewed scientific journal, U.S. companies imported more than 1,400 metric tons on chrysotile asbestos, primarily from Canada, in 2008. Much of it is used for roofing products. In addition, the U.S. imports large quantities of asbestos-containing products such as cement pipe, asbestos-lined brake pads and gaskets.
According to global estimates reported by the World Health Organization 125 million people are exposed to asbestos in the workplace and more than 107,000 people die each year from asbestos-related mesothelioma, lung cancer and asbestosis resulting from occupational exposures. Many experts believe current estimates of asbestos-related disease and deaths understate the actual numbers. Since mesothelioma did not receive its own classification in the International Classification of Diseases until the mid-1990s, many asbestos-related deaths were not classified as such.
Given the decades-long latency period from exposure to asbestos to development of mesothelioma, the epidemic of asbestos-related diseases is still spreading and will for decades to come, particularly in countries still heavily using asbestos.
Guidelines for Mesothelioma Treatment
The incidence of malignant mesothelioma, a respiratory cancer associated with inhaling asbestos, is expected to double in many countries in the next 20 years, according to the European Society of Medical Oncology. In the United States, approximately 2,500 to 3,000 people die of mesothelioma each year.
In an article in the July issue of the Annals of Oncology, the European Society of Medical Oncology outlines treatment guidelines for patients with mesothelioma. The clinical practice guidelines are developed by the non-profit professional organization, which promotes advances in cancer treatment and prevention, to assist doctors and patients in making decisions about appropriate health care. According to the practice guidelines:
Patients with mesothelioma often first have symptoms of shortness of breath due to excess fluid in the chest. Patients with more advanced cases may have chest pain. A chest x-ray or scan may suggest a case of mesothelioma based on thickening of the membrane lining the the lung called the pleura. Laboratory examination of chest fluid can confirm a diagnosis of mesothelioma. But the lab reports are often equivocal.
Doctors should interview the patient about their work history to try to determine if they were exposed to asbestos in their workplace, the most common cause of mesothelioma. Most cases of mesothelioma are due to occupational exposure
The gold standard for diagnosis of mesothelioma is a microscopic examination of specific antigens in a tissue biopsy obtained through a surgical procedure called a pleuroscopy. A surgical instrument is inserted into the patient’s chest through an incision to collect tissue. Research studies suggest that certain proteins and oseteopontin, a human gene product, are useful indicators to support a diagnosis of mesothelioma.
After doctors confirm a diagnosis, a CT scan of the patient’s chest is used to assess the advancement of the cancer. An accurate assessment of the mesothelioma’s stage is essential to determine the most appropriate treatment and the patient’s prognosis. Malignant pleural mesothelioma rarely spreads to distant parts of the body, but patients often have advanced localized cancer in their respiratory system when they are diagnosed.
Various surgical procedures have been used with varying degrees of success, according to the European Society of Medical Oncology. Surgery should be performed only on patients with less advanced cases of mesothelioma as part of a multi-pronged approach to treatment combined with chemotherapy and/or radiation. The use of radiation in treating mesothelioma has been limited because of the difficulty of irradiating such a large area of the body as a lung without irreparably harming the adjacent healthy lung. Still, it is used.
As far as chemotherapy, the use of combinations of cancer drugs, permetrexed and cisplatin, and to a lesser extent, raltitrexed and cisplatin, have led to improved survival results in patients as well as lung function and symptom control, compared to use of cisplatin in clinical trials. The combination of permetrexed and carboplatin is an effective alternative chemotherapy.
University of Arizona’s Cancer Center Hopes to Become Premier Mesothelioma Treatment Facility in the Southwest
Mesothelioma patients now have a comprehensive treatment center in the Southwestern region of the United States at the University of Arizona. Staffed by a nationally recognized mesothelioma oncologist, thoracic surgeon, and radiologist, the University Medical Center offers patients treatment options that were previously only available in California, or as far away as Massachusetts.
Mesothelioma is a rare form of cancer typically affecting the lining of the lungs. Primarily caused by exposure to airborne asbestos fibers, mesothelioma is highly aggressive and is resistant to many standard cancer treatments. Currently there is no known cure for mesothelioma, and the average survival time without treatment varies from 4 – 18 months after diagnosis.
Jonathan C. Daniel, MD, Thoracic Surgeon and Assistant Professor in the Division of Cardiothoracic Surgery in the University of Arizona Department of Surgery, previously of Brigham and Women’s Hospital in Boston, now offers extrapleural pneumonectomy or radical pleurectomy surgery. Since his arrival in Arizona, Daniel has performed 5 of the complex surgical procedures.
The procedure involves removal of the tumor and the affected lung and parietal pleura, as well as the possible removal of the diaphragm, the pericardium and other extrapleural tissue. The visceral pleura is attached to the lung and is therefore removed with it. Once the structures are removed, they are reconstructed using a mesh fiber or synthetic material that has been designed to replace the tissues and the supporting functions they previously performed.
The surgery is preceded by chemotherapy treatment from mesothelioma oncologist Linda Garland, MD and followed by intensity modulated radiation by Alexander Chi, MD. “A cure with mesothelioma is really hard to achieve,’’ Dr. Daniel said. “We are trying to extend life.”
One of Dr. Daniel’s patients, James Massie, is currently free of the disease and is looking forward to life with his wife and “hiking, camping, [and] just enjoying each other’s company.”
University of Arizona Mesothelioma Treatment Center
Researchers Report Clearer Understanding of How Asbestos Causes Mesothelioma
The paradox of how asbestos kills cells and yet spurs growth of cancerous tumors has perplexed scientists for decades. A group of scientists led by researchers at the University of Hawaii claim to have new insights into the process. Their research may offer new tools to identify people at risk of developing mesothelioma and to prevent or slow tumor growth in people already diagnosed with asbestos-related disease.
Thousands of Americans have been exposed to asbestos and are at risk of developing malignant mesothelioma, a cancer of the lining of the lung or abdomen. Approximately 2,000 to 3,000 people die of mesothelioma each year in the United States and tens of thousands more worldwide. In addition, asbestos exposure raises the risks that smokers will develop lung cancer.
But the long latency period of 30 to 50 years from asbestos exposure to the appearance of tumors may offer a window of opportunity to block the trigger mechanism that causes asbestos-related cancer.
People often unknowingly inhale microscopic asbestos fibers at workplaces and the fibers can permanently lodge in the lung, causing inflammation. Most human cells exposed to asbestos die within 24 to 48 hours. Dead cells should not be able to multiply and form tumors. So how do cancerous tumors eventually form?
In an article in the Proceedings of the National Academy of Sciences, the researchers describe how asbestos kills cells through a process called programmed cell necrosis that leads to the release of a molecule called mobility group box 1 protein or HMGB1. The protein begins an inflammatory chain reaction in tissue that causes the release of mutagens that promote tumor growth. Cancer often occurs in the presence of chronic inflammation.
Asbestos exposure leads to elevated levels of HMGB1 in the blood, the researchers note. In the study, people with a history of asbestos exposure had HMGB1 levels that were more than four times higher than those of healthy people who had not been exposed.
The researchers say that mesothelial cell death and release of HMGB1 function as triggers in mechanism that leads to asbestos-related cancers. Based on that, they suggest it may be possible eventually to target HMGB1 to treat mesothelioma and identify groups of people who have been exposed to asbestos by simple blood tests to measure HMGB1 levels. By interfering with the inflammatory reaction prompted by asbestos, it may be possible to decrease the occurrence of mesothelioma and reduce the rate of tumor growth among people already diagnosed with mesothelioma.
In the future, therapeutic approaches aimed at blocking chronic inflammation and in particular the protein HMGB1 could reduce the risk of malignant mesothelioma among workers exposed to asbestos.
To test their theory, the lead researchers, Drs. Haining Yang and Michele Carbone of the University of Hawaii plan to conduct a clinical trial in Cappadocia, Turkey, where more than 50 percent of the population of two rural villages dies of mesothelioma from exposure to mineral fibers used in building materials. If the trial produces positive results, they plan to try a similar approach on groups of people exposed to asbestos in the U.S.
Researchers Identify Suppressor of Mesothelioma Cell Growth
By Wade Rawlins
In the last few years, microRNAs have received lots of attention as one of the most significant scientific and medical discoveries. They appear to play a major role in reprogramming a cell to undergo uncontrolled cell division, causing growth of cancerous tumors.
An important new study published this month in The Journal of Biological Chemistry suggests the potential for using microRNAs in innovative treatment therapies to suppress tumor growth in patients with malignant mesothelioma.
Mesothelioma is a cancer associated with asbestos exposure that affects the lining of the lungs or abdomen. It is an aggressive cancer that is often resistant to chemotherapy and radiation treatments. In the United States, 2,000 to 3,000 new cases of mesothelioma are diagnosed each year.
All people —all living organisms in fact—have DNA and RNA, which are the basic building blocks of life. Each microscopic DNA molecule contains hundreds of millions of atoms in a unique sequence with the genetic information to construct cells. RNA translate the genetic information into specific instructions. MicroRNA’s are single stranded molecules that regulate gene expression. “They have been described as the body’s ‘master switches,’” according to Kenneth A. Berlin, president and CEO of Rosetta Genomics, Ltd., a developer of microRNA products used for cancer diagnostic tests.
Abnormal expression of microRNA’s has been linked to the growth of cancer, but researchers haven’t understood well the mechanics of what was occurring at a cellular level.
In the new study, medical researchers from Vanderbilt University School of Medicine, New York University Langone Medical Center and Rosetta Genomics, Ltd., analyzed cancer tissue from eight patients with advanced mesothelioma to pinpoint microRNAs linked to the progression of pleural mesothelioma, a cancer of the lining of the lung.
The researchers observed that mesothelioma cancer cells failed to express miR-31, a particular microRNA that has been linked to suppression of breast cancer tumors in mice. An assessment of miR-31 revealed its ability to inhibit the proliferation and invasion of mesothelioma cells. When researchers re-introduced miR-31 into malignant mesothelioma cells, they observed that it significantly inhibited the multiplication and formation of colonies of cancer cells.
The researchers said their analysis demonstrated that miR-31 profoundly affected cell cycle progression in malignant mesothelioma cells.
Researchers have previously connected the loss of the 9p21.3 chromosome in malignant mesothelioma cells with a rapid recurrence of tumors. In the latest research, they say the association of the loss of miR-31 with the deletion of the 9p21.3 chromosomal region and enhanced capacity of cancer cells to proliferate opens new opportunities for treatment of malignant mesothelioma and other tumors.
A study published earlier this year suggested the presence of even a single specific microRNA has significant value for predicting the course that a mesothelioma patient’s disease will take. Using microRNA as a guide, the researchers were able to accurately divide the patients who had undergone surgery to remove tumors into two groups: those that would survive more than a year after surgery, and those that would die within 12 months. Elevated amounts of microRNA were associated with decreased spread of cancer and longer survival.
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