A GIST cancer is a very rare form of growth that can occur in the stomach or small bowel. They belong in the ‘family of tumors' known as sarcomas.
50% of these tumours can occur in the stomach, but to put it in proportion they only make up 1-3% of all gastric malignancies.
They originate from cells that occur in the stomach and small bowel known as ICC’s or Interstitial Cells of Cajel.
These cells are part of the guts neurological pacemaker system, allowing contraction of smooth muscle cells in the stomach. It is this co-ordinated contraction that helps digestion and passage of your food.
Mutations occur in these cells which then actively divide in a similar way to other cancers causing both local spread as well as metastasising or spreading elsewhere in your body.
The cause of GIST cancer is unknown, although it does involve changes or mutations in DNA, the genetic material which determines are very being.
Lifestyle, smoking and the environment in which we live may all play a part as well as genetics.
Sometimes this tumor can cluster in families, although in most cases they occur “sporadically” without any family link.
Some genes are known as oncogenes, genes which promote tumor growth, although these are usually inactive as other genes known as TSG’s or tumor suppressor genes exert an influence to keep them switched off.
The cause of them becoming active is unclear although this could partly be due to the suppressor genes failing because of mutation or mutation of the oncogene itself.
In GIST’s there are oncogenes known as c-kit (90%) and PDGFRA (5-10%), often mutated, which code for receptor proteins called Kit (CD 117) and PDGFRA.
These bind “ligands” which switch cells on through a series of chemical signals and pathways, resulting in stimulation of cells to grow and divide.
It is this growth and division that causes GIST cancer's to form, a kind of domino effect.
They cause similar symptoms to other forms of stomach cancer.
The tumors can bleed, cause early satiety (feeling full quickly), nausea, vomiting, weight loss, indigestion and tiredness.
Sometimes they are found as an incidental finding during an endoscopy test.
The diagnosis is usually confirmed on investigation. When you visit your doctor, they may pick up a mass in your abdomen on examination. On testing your blood, the might find that you are anemic prompting further investigation.
For stomach GIST, the most common way of diagnosing it is on an endoscopy or flexible camera examination of your stomach.
During the test, biopsies or pieces of tissue will be taken which can be examined in the laboratory. Doctors look for active “mitotic” cells or cells that are actively dividing.
Other investigations may also help in the investigation including:
Treatment can be divided in to surgical and medical management.
Surgery is by far the most common way of dealing with this form of tumor.
This can be curative, but if the tumor is too big or spread then biologic treatment with a drug called Imatinib, Gleevec or Glivec may be used to help treat your tumour.
Other forms of chemotherapy and radiotherapy have been tried, but are less effective.