An introduction to how GIST is diagnosed
The process of identifying a disease is known as diagnosis. To detect and diagnose gastrointestinal stromal tumor (GIST):
- The doctor will conduct specific exams and tests, including taking a detailed medical history and performing a thorough physical exam.
- If a mass is suspected, imaging tests such as CT, MRI scans or endoscopy will help to identify the suspicious area and will determine whether the disease has spread.
- The imaging tests alone cannot tell if the mass is GIST. The only way to know is by obtaining cells from the abnormal area through a biopsy.
Biopsies are sometimes done at the time of surgery (surgical biopsy), but in many cases biopsies are done prior to surgery and can sometimes be done during an endoscopy (endoscopic biopsy). In some cases, a needle (fine needle aspiration (FNA) biopsy) is inserted through the skin and into the suspected tumor. Biopsies must be done carefully so as not to break apart the tumor which might cause bleeding or possibly increase the risk of cancer spreading.
- When a tumor is found and a sample is obtained through biopsy, a histologic examination will be performed by a pathologist. This is the process of looking at the suspected tumor sample under a microscope to determine malignancy.
Once a pathologist has the tissue, he/she will look at various things including the appearance of the cells. They will also apply special stains to the tissue. These stains tell the pathologists whether or not particular proteins are present on the cell which help establish the diagnosis of GIST. Further specialized testing, such as mutational testing, can help identify the subtype of GIST.
- A pathology report will be issued to you and your doctor and it usually provides the information required to estimate the risk of a recurrence of GIST after surgery. Your pathology report is key to understanding GIST. Here is a simple guide on how to read it: https://liferaftgroup.org/2015/10/your-pathology-report-the-key-to-understanding-your-gist/