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NCCN Guidelines for Patients



Malignant Pleural Mesothelioma, Version 1.2016


About mesothelioma

What are the risk factors?

What are the risk factors?

A risk factor is something that increases the chance

of getting a disease. Risk factors can be activities

that people do, things in the environment, or traits

passed down from parents to children through genes.

Doctors know some risk factors are linked to specific

cancer types. When it comes to mesothelioma,

exposure to asbestos is the only known risk factor.

Asbetos is the primary cause

Asbestos is a group of minerals made of tiny fibers.

It is strong, flexible, and resistant to heat and fire.

Because of these traits, asbestos has been used in

housing and commercial products, such as roofing

and brake pads.

Asbestos can break into tiny pieces that may be

breathed in or swallowed. The asbestos pieces can

then get trapped in the lungs and remain there for

years. How asbestos gets into the pleura (the tissue

lining around the lungs) and causes normal cells

to become cancer cells isn’t fully known. It often

takes 20 to 40 years after having had contact with

asbestos for mesothelioma to develop. There are no

studies that clearly show the length of time exposed

to asbestos that is needed to increase the risk for


Asbestos is divided into two main groups:



Serpentine is made of long, curly fibers.



Amphibole is made of straight, needle-like


There are different types of asbestos within each

main group, but the most commonly used include

chrysotile, crocidolite, and amosite. Of these three,

chrysotile is the most widely used to make products.

Chrysotile is a type of serpentine asbestos. Its long,

curly fibers make it less likely to break into pieces

and cause mesothelioma. Crocidolite and amosite

are types of amphibole asbestos. They are used less

frequently because their straight, needle-like fibers

are more brittle and likely to break, or fragment.

However, because they fragment, they are more

likely to be breathed in or swallowed and cause


Other possible risk factors

Some patients with mesothelioma have had no clear

exposure to asbestos. This suggests that there may

be other causes of the disease. A gene mutation is

an abnormal change in the instructions for making

and controlling cells. Recent studies show that

having a mutation in the


gene may increase

the risk for mesothelioma. However, the cause-and-

effect relationship between asbestos exposure and



mutation is uncertain. This gene mutation

can rarely be passed down from parents to children.

Prior radiation therapy, such as that given for

Hodgkin lymphoma, may also be a cause.


Smoking does not appear to put you at risk for

mesothelioma. If you smoke and have contact with

asbestos, you have an increased risk for lung cancer.

If you are diagnosed with mestothelioma and smoke,

it is suggested you quit since smoking may interfere

with cancer treatment. Read more about smoking in

Part 5,

Supportive Care