Asbestos and its relation to mesothelioma: historical evolution

In most Western countries there are three phases in exposure to
amianto.41 The first phase is associated with the extraction and manufacture of asbestos material
that began between 1920 and 1930; although the intensity of exposure was very high, the
number of workers affected was limited. The second phase, from 1940,
characterized by the industrial use of asbestos-scale manufacture of ships, trains,
automobiles, textiles and electrical products, buildings, homes and factories; at this stage
produced a substantial increase in the number of exposed workers. The third phase, more
recent, is the non-occupational and occupational exposure to the millions of tons
asbestos placed in the second phase, they begin to deteriorate with use and
maintenance and to release fibers; although this represents an exposure dose
relatively low, it is very broad and generalized.
      Although there are some earlier references regarding possible harmful effects of
Asbestos was in 1920 when I first respiratory effects were described
fibrosis caused by inhaled asbestos and applied the term 'asbestosis' .42 In 1931
warned at a conference of the British unions possible relationship to cancer

Pleural mesothelioma and environmental exposure to asbestos
lung, although the first cases of cancer in asbestos workers brocopulmonar
appeared in the medical literature in 1934. In 1943 the German government was the first to
recognize lung cancer induced by exposure to asbestos and disease
professional entitled to compensation. In 1953 lnspection UK Working
asbestos included in their list of carcinogens. During the 40's and 50 major
research on the effects of asbestos were performed on request by the industry itself,
which by then was at the height of its expansion and tried to prevent such results
made public. In 1955 R. Doll published the first epidemiological study on the relationship
between asbestos and lung cancer, despite the opposition of the company Turner & Newall,
he had commissioned research. In this classic work is estimated that mortality
lung cancer in workers exposed to asbestos for 20 years, was
about 10 times higher than in the population general.43
     Besides pulmonary involvement, pathologists had observed in autopsies of
asbestos workers various alterations of the pleura, as plaques and effusions and
a rare type of tumor initially tagged as 'endothelioma'. In the 40 already
suggested its possible relation to asbestos, and in the following years also reported
peritoneal occurrence of localization of such tumor, and referred to as
'Mesothelioma'. However, until the late 50s was considered a pathology very
infrequent and of little interest. That assessment changed dramatically when a group of
physicians and pathologists revealed the existence of a real 'epidemic' of
mesotheliomas mines around Cape in South Africa, despite the efforts of the
mining company to cover it up. The research, which firmly established the association
between mesothelioma and asbestos exposure, was published in 1960 to great acclaim,
being one of the most cited papers in the field of medicine ocupacional.44 The relationship
with this high tumor malignancy was what determined the change in the consideration of
Asbestos 'magic mineral' a 'killer dust'.
      Once the risk caused by mineral extraction, the relationship between
MMP asbestos and quickly spread to the manufacture of asbestos products or
intensive activities thereof, as the insulation industry,
characterized by high exposure dose, with clearly identifiable sources and
affecting a relatively small group of workers. But while diminished
or exposure to high doses are controlled, the use of asbestos became general in
multiple processes and products. A further aspect to be considered is the controversy
the role of asbestos fiber such as that to the time a change occurred in the
risk groups generalized the use of chrysotile. From the observation of a higher
risk associated with exposure to crocidolite, or blue asbestos, and amosite, both amphibole

Mechanisms of action, carcinogenicity

Some of the effects of asbestos in the body are associated with the characteristics
Physicochemical fibers 21,22 such as diameter, length, and composition stability
chemistry. The fiber diameter determines the breathability; only those which have a diameter
less than 3 microns reach the alveoli. Moreover, a larger diameter and length favors
the deposition of fibers in the bronchial and bronchiolar branching, while reducing
Once the amount of fibers which reach the alveolar compartment. The fibers deposited
mucociliary epithelium can be partially eliminated with the mucus, whereas
those that reach the alveolar or interstitial space can be partially eliminated or
modified by macrophages. The action of macrophages is especially effective on
Smaller fibers. Chrysotile, which can be broken into multiple small microfibers
length and diameter and is acid sensitive is removed by this mechanism in a
greater than amphiboles, which thus have greater biodurability and biopersistence.
Experimental studies in animals suggest that the fibrogenic potential and
carcinogenic asbestos is related to the number of fibers over 5-8 um
length. Another aspect that justifies the higher biological activity of amphiboles is their
composition, the presence of iron in the surface of amosite and especially of
crocidolite, largely determines the production of free radicals (ROS / RNS, reactive
oxygen species, reactive nitrogen species).
     The mechanisms by which asbestos fibers reach the pleura are still poorly
conocidos.23 Some experimental studies suggest that it could be from space
the visceral pleura alveolar directly or via the lymphatic system, the existence of
connections between lung and pleural lymphatics. It seems unlikely that the fibers
reach the pleura via the blood, although it can not be excluded. In any case, the
distribution of asbestos fibers in the pleura is not homogeneous, focusing on points
specific to the parietal pleura next to the rich lymphatic vessels in macrophages, cells
Plastic and lymphocytes, similar to the 'black spots' of antracosis.24
Although it is accepted that the fibers of all types of asbestos are capable
genotoxic not possible acción.25 The mechanisms are not completely known
involvement of cellular DNA could be the result of oxidative damage from free radicals
produced by the action of ions from the surface of the fibers. It could also happen
ROS that DNA and other substances (cytokines, growth factors and others affecting
intracellular signal mediators) originating from a chronic inflammatory process
persistent. In this case it would carcinogenesis related fibrogénesis.26 27


The term asbestos or asbestos generically designates a group of minerals 
very resistant to heat, abrasion strength and fibrous. Asbestos is the source word 
Latin and means 'incorruptible'; Asbestos is of Greek origin and means 'fireproof'. It 
silicate complex is formed by bundles of fibers (crystal structure whose ratio 
length to diameter ratio is greater than 3). From the mineralogical point of view are distinguished 
two types: serpentine and amphibole. The streamers are one variety, chrysotile 
or white asbestos. It is a magnesium silicate and easily separable flexible fibers, very 
long and thin, with a diameter of 0.02-0.03 microns. The amphibole group includes several 
compounds, the principal of which are crocidolite (riebeckite or blue asbestos) and 
amosite (grunerite or brown asbestos). Both are magnesium iron silicates, although the 
crocidolite also contains sodium. Amphibole fibers are straight and a diameter 
considerably higher than that of chrysotile crocidolite 0.06-1.2 um, 0.15-1.5 microns the 
amosite. There are three other varieties of amphibole, anthophyllite, tremolite and actinolite, 
though they have little or no value comercial.21, 22 
      The three types of asbestos share the characteristics of heat resistance, 
mechanical, electrical and chemical. Chrysotile is the most flexible, while amosite is 
variety of higher hardness. The three are resistant to the action of alkalis, but chrysotile 
is vulnerable to the action of acids. To a lesser extent, is also amosite 
partially sensitive to acids, whereas crocidolite is very sturdy. these 
features make the asbestos has been widely used in all kinds of processes 
Industrial: as material for thermal and acoustic insulation, building, piping (on 
form of cement), in developing tissues with insulating properties, in 
construction and insulation of ships and trains in the automotive industry (friction) in 
power plants and refineries, and in many consumer products that 
require resistant and insulating elements. Currently almost 90% of the asbestos is 
chrysotile variety, the main producers and exporters are Canada (Quebec) 
Russia. Amphibole, plus some mines located in Australia, come 
mainly from South Africa. World production of asbestos has been declining in 
recent years, rising more than 5 million tons per year in the decade of the 70 
less than 3 million in 1998.22

Malignant mesothelioma

the pleura (between 70 and 90% of cases), less frequently in the peritoneum and very
rarely in the pericardium and the tunica vaginalis testis. It is a rare tumor, which
mainly affects men over 60 years of age, associated with asbestos, and
a long latencia.1
     From the macroscopic viewpoint malignant mesothelioma of the pleura (MMP) is
presents as multiple nodules in the visceral pleura and especially the parietal, which tend to
produce coalescence and pleural effusions. Very rarely some pleural tumors
have localized benign, so initially it was known as the MMP
'Diffuse mesothelioma'. The tumor grows by local extension of the pleural serosa, forming
mass invading adjacent tissues and structures, rather than spread
hematogenous. Three histological types: more than half of the patients have an
epithelial pattern; the sarcomatous (mesenchymal or fibrous) is less frequent, and almost
a third portion of MMP have a mixed pattern with cell characteristics
intermedias.1 is important to distinguish the epithelial MMP metastases of adenocarcinomas
other organs, especially lung, for his great ability to metastasize in
pleura. To distinguish immunohistochemical techniques are required, especially
determination of carcinoembryonic antigen (CEA), and negative in mesotheliomas
positive carcinomas. Cytokeratin immunoreactivity is important to
distinguish fibrous mesothelioma metastasis to other undifferentiated sarcomas.
      Chest pain and dyspnea are the most common initial symptoms. The pain is usually
diffuse, persistent and progressive. Later accompanied by cough, dyspnea, impaired
restrictive lung function, and symptoms such as weight loss, fatigue or
fever. MMP diagnosis should be considered in any patient with stroke or
pleural thickening, especially if accompanied by pain. The previous history of
asbestos exposure is an additional element of diagnostic importance. Although in the
radiology are typical pleural thickening and effusions, the definitive diagnosis

Asbestos is a generic term applied to a group of fibrous silicates

Asbestos is a generic term applied to a group of fibrous silicates. There are three
commercially important forms: chrysotile, crocidolite, and amosite. All of them are
carcinogenic, capable of causing mesothelioma and lung cancer. Malignant mesothelioma is
a rare tumour mainly located in the pleura. Most mesotheliomas are fatal within 12-24
months of diagnosis, and have a latency period of 20-50 years. There is strong evidence
supporting the causal association between mesothelioma and occupational exposure to
asbestos. Nevertheless, with the virtual cessation of high-dose occupational exposure to
asbestos, public health attention has turned to the risks of exposure at lower doses arising
from non-occupational sources. Domestic exposure results from asbestos fibres brought
home by workers exposed in the workplace. Environmental exposure may result from
residence in the vicinity of a single well-identified source of asbestos pollution. However,
further studies are needed to investigate whether the industrial and domestic use of asbestos
may produce sufficient environmental pollution to cause mesothelioma.
A population-based case control study was carried out in six areas from Italy, Spain and
Switzerland, including 215 new histologically confirmed cases of pleural mesothelioma and
448 controls. A panel of industrial hygienists assessed the probability and intensity of
asbestos exposure separately for occupational, domestic and environmental sources. Each
occupational period was classified based on the information collected in the occupational
history. Classification of domestic and environmental exposure of each residence was based
on the presence and use of asbestos at home, asbestos industrial activities in the
surrounding area and their distance from the dwelling.
Among 53 cases and 232 controls without evidence of occupational exposure to asbestos,
handling asbestos material or presence of asbestos material at home susceptible to damage,
as well as living within 2000 m of asbestos industries was associated with increased risk of
mesothelioma. Typically these circumstances entail exposure to concentrations ranging from
0.1 to 5 f/l, about 1000 times lower than those measured in occupational settings. Among the
132 cases and 257 controls in the Spanish centres the main occupations with increased risk
of mesothelioma were manufacture of asbestos cement, launderers, cleaners and pressers,
electrical fitters, plumbers, and drivers of material-handling and related equipment. Almost
88% of mesotheliomas were attributable to asbestos exposure, 62% due to occupation and
26% from non-occupational origin.
Utilisation of asbestos has almost completely ended in most developed countries as the
result of government bans. Nevertheless, asbestos manufacture continues in parts of the
developing world. Even countries that have banned the material still have to devise
strategies to cope with the asbestos that remains in place, monitoring potential effects of
fibres used as asbestos substitutes, and surveillance of former asbestos workers and
exposed populations in order to provide them with access to compensation

Complementary and alternative therapies for malignant mesothelioma

When you have cancer you are likely to hear about ways to treat your cancer or relieve
symptoms that your doctor hasn’t mentioned. Everyone from friends and family to
Internet groups and websites may offer ideas for what might help you. These methods
can include vitamins, herbs, and special diets, or other methods such as acupuncture or
massage, to name a few.
What exactly are complementary and alternative therapies?
Not everyone uses these terms the same way, and they are used to refer to many different
methods, so it can be confusing. We use complementary to refer to treatments that are
used along with your regular medical care. Alternative treatments are used instead of a
doctor’s medical treatment.
Complementary methods: Most complementary treatment methods are not offered as
cures for cancer. Mainly, they are used to help you feel better. Some methods that are
used along with regular treatment are: meditation to reduce stress, acupuncture to help
relieve pain, or peppermint tea to relieve nausea. Some complementary methods are
known to help, while others have not been tested. Some have been proven not be helpful,
and a few have even been found harmful.
Alternative treatments: Alternative treatments may be offered as cancer cures. These
treatments have not been proven safe and effective in clinical trials. Some of these
methods may pose danger, or have life-threatening side effects. But the biggest danger in
most cases is that you may lose the chance to be helped by standard medical treatment.
Delays or interruptions in your medical treatments may give the cancer more time to
grow and make it less likely that treatment will help.
Finding out more
It is easy to see why people with cancer think about alternative methods. You want to do
all you can to fight the cancer, and the idea of a treatment with few or no side effects
sounds great. Sometimes medical treatments like chemotherapy can be hard to take, or
they may no longer be working. But the truth is that most of these alternative methods
have not been tested and proven to work in treating cancer.
As you consider your options, here are 3 important steps you can take:
• Look for “red flags” that suggest fraud. Does the method promise to cure all or most
cancers? Are you told not to have regular medical treatments? Is the treatment a
“secret” that requires you to visit certain providers or travel to another country?
• Talk to your doctor or nurse about any method you are thinking about using.
• Contact us at 1-800-227-2345 to learn more about complementary and alternative
methods in general and to find out about the specific methods you are looking at. You

Chemotherapy for malignant mesothelioma

Chemotherapy (chemo) is treatment with anti-cancer drugs. There are 2 main ways that
chemotherapy can be given to treat mesothelioma.
In systemic therapy, chemotherapy is injected into a vein. The drug enters the
bloodstream and travels throughout the body to reach and destroy the cancer cells
wherever they may be.
Chemo drugs can also be placed directly into the body cavity where the cancer is – either
intrapleurally (directly into the chest) or intraperitoneally (into the abdomen) – with a
small catheter (tube) placed through a small cut in the chest or abdominal wall. Chemo
drugs given this way are still absorbed into the bloodstream, but the highest concentration
of the drug goes directly to where the cancer cells are.
Chemo drugs are sometimes heated before they are placed directly into a body cavity
(called hyperthermic chemotherapy), which may help them work better. Sometimes this
treatment is given as a single dose in the operating room, right after surgery to remove
the cancer. This approach is called heated intraoperative chemotherapy or HIPEC. It is
more often used to treat peritoneal cancers, in which case it may be called heated
intraperitoneal chemotherapy.
For mesotheliomas that can be treated with surgery, chemotherapy may be given before
surgery to try to shrink the cancer and lower the risk of spread. This is called neoadjuvant
Chemo can also be given after surgery to try to try to kill any cancer cells that were left
behind because they were too small to be seen. This type of treatment, called adjuvant
therapy, may help delay or prevent the cancer growing back.
For cancers that are not resectable, chemotherapy may be the main treatment (alone or
along with radiation therapy). Chemotherapy may slow the progression of the disease, but
it is very unlikely to make it go away completely.
Doctors usually give chemotherapy in cycles, with each period of treatment followed by a
rest period to allow the body time to recover. Chemo cycles generally last about 3 to 4
weeks. Chemotherapy is often not recommended for patients in poor health, but advanced
age by itself is not a barrier to getting it.
Several chemo drugs have been used to treat mesothelioma. Most doctors now use a
combination of the drugs pemetrexed (Alimta®
) and cisplatin. Pemetrexed lowers levels
of folic acid and vitamin B12 in the body, so patients get these as well to help avoid
certain side effects. Other combinations that may be used include pemetrexed with
carboplatin and cisplatin with gemcitabine (Gemzar®
Other drugs used to treat mesothelioma include: