Genetic mutations, or abnormal changes in genes, can cause cancer by making cells in the body grow and spread when they are not supposed to. In GIST, genetic mutations lead tumors to develop along with the normal cells of the gastrointestinal tract.
BRAF, B-Raf proto-oncogene, serine/threonine kinase; KIT, KIT proto-oncogene receptor tyrosine kinase; KRAS, KRAS proto-oncogene, GTPase; NF1, neurofibromin 1; PDGFRA, platelet-derived growth factor receptor alpha; SDH, succinate dehydrogenase.
aSDH deficiency refers to a decrease in succinate dehydrogenase (SUX-sin-ate dee-high-DRAW-jen-ase), a protein. The decrease can develop from mutations in specific genes.
Reference: Bartholomew AJ, Dohnalek H, Prins PA, et al. Underuse of exon mutational analysis for gastrointestinal stromal tumors [abstract]. J Surg Res. 2018;231:43-48. doi:10.1016/j.jss.2018.05.014
Confirming your specific mutation through mutational testing is the best way to ensure that your treatment plan is right for your type of GIST.
A sample of your tumor tissue is tested to learn which mutations are driving your GIST. The tissue needed for the test might already be available if you have had surgery for GIST. Tumor tissue is stored for several years after surgery so that taking another sample usually should not be necessary.
What is immunohistochemistry, or IHC staining, for KIT?
This type of test helps your doctor determine whether the tissue removed (or resected) is GIST or something else. It may lead to a report that says your GIST tests positive for KIT, but it is not the same as mutational testing. It cannot confirm if you have a KIT mutation.
Ask your care team when you will get your results. They may recommend that you start a treatment before you receive them.
Some test results may not include your exon, but results should always include information about your gene and alteration. The alteration listed in mutational test results can represent a change in the amino acid or DNA change. Ask your doctor to explain what this means for you.
Without knowing the gene and alteration that are driving your GIST, you may be starting treatment with incomplete information.
Testing as soon as possible is best. This improves your chances of avoiding treatments that don’t work and starting one that is most likely to help. The results of mutational testing may give your doctor answers to these questions:
GIST is a rare and complex type of cancer. Your treatment should be the right one for the exact mutation causing it. The first treatment (called first-line treatment) for most patients who have advanced GIST is the drug imatinib.
Reference: Bannon AE, Klug LR, Corless CL, Heinrich MC. Using molecular diagnostic testing to personalize the treatment of patients with gastrointestinal stromal tumors. Expert Rev Mol Diagn. 2017;17(5):445-457.
New treatments for GIST are being developed. It may be possible for patients to get them by being part of a clinical trial. Talk with your doctor to learn if you are able to join a clinical trial for your GIST.
Blueprint Medicines and patient advocacy organizations are committed to increasing mutational testing in GIST. Find more information about GIST from experts, as well as support for patients and caregivers, at the following websites: