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A risk factor is anything that affects a person's chance of
getting a disease such as cancer. Different cancers have different risk
factors. For example, exposing skin to strong sunlight is a risk factor
for skin cancer. Smoking is a risk factor for cancer of the lung, and
many other cancers. But risk factors don't tell us everything. Having a
risk factor, or even several, does not mean that a person will get the
disease. And many people who get the disease may not have had any known
risk factors.
Currently, there are very few known risk factors for GISTs.
Genetic syndromes
Most GISTs are sporadic (not inherited) and have no clear
cause. In rare cases, though, GISTs have been found in several members
of the same family. These family members inherited a gene mutation that
can lead to GISTs.
Familial gastrointestinal stromal tumor syndrome: This is a
rare, inherited condition that leads to increased risk of developing
GISTs. People with this inherited condition tend to develop GISTs at a
younger age than GISTs usually occur. They are also more likely to have
multiple GISTs. Most often, this syndrome is caused by an abnormal copy
of the c-kit gene
that is passed from parent to child. The c-kit gene is the
same gene that is mutated (changed) in most sporadic GISTs. In people
who inherited the abnormal gene, it is present in all the cells of
their body, while in people with sporadic GISTs it is only found in the
cancer cells. In a few cases, an abnormal copy of a different gene, the
PDGFRA
gene, causes this genetic syndrome. Defects in the PDGFRA gene are
found in about 5% of sporadic GISTs. Sometimes people with familial
GIST syndrome also have skin spots like those seen in patients with
neurofibromatosis (discussed below). Before tests for the c-kit and PDGFRA genes became
available, some of these people were mistakenly thought to have
neurofibromatosis.
Type 1
Neurofibromatosis (or von Recklinghausen's disease): Is a
disease that is often inherited. It is caused by defects in the gene NF1. People
affected by this syndrome have many benign tumors that form in nerves
(called neurofibromas). These tumors form under the skin and in other
parts of the body. They also have a certain type of tan or brown spots
on the skin (called café au lait spots). People with this
condition have a high risk of GISTs and many other cancers.
Last Medical Review: 05/11/2009
Last Revised: 05/11/2009
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