A risk factor is anything that affects a person's chance of getting a disease like cancer. Different cancers have different risk factors. For example, 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 have few or no known risk factors.
Currently, there are very few known risk factors for gastrointestinal stromal tumors (GISTs).
Older age
These tumors can occur at any age, but they are rare in people younger than 40 and are most common in people in their 60s.
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 condition tend to develop GISTs at a younger age than when they 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 (see "Do we know what causes gastrointestinal stromal tumors?"). In people who inherited the abnormal gene from a parent, 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.
Neurofibromatosis type 1 (or von Recklinghausen disease): This disease is caused by a defect in the NF1 gene. This gene change may be inherited from a parent, but in some cases it occurs before birth, without being inherited.
People affected by this syndrome often have many benign tumors that form in nerves (called neurofibromas), starting at an early age. These tumors form under the skin and in other parts of the body. These people also have a certain type of tan or brown spots on the skin (called café au lait spots).
People with this condition have a higher risk of GISTs, as well as some other types of cancer.
Feedback
