Your GIST Treatment Guide
Is GIST Treatment Working?
With most cancers, doctors measure whether or not a treatment is working with one main yardstick: is the tumor shrinking, growing, or staying the same? If the tumor isn’t growing, or is even getting smaller, that’s a sign that the treatment is effective. When a tumor grows while a patient is on a certain drug, doctors will usually stop that drug since it isn’t controlling the cancer.
GIST is different. In the metastatic setting, when GIST is evaluated by CT scan or MRI scan to check treatment response, tumors may enlarge, or stay the same size, even though the patient is improving. A PET scan can help in these cases because they show tumor activity instead of tumor size. This fact is unique to GIST.
Treatments You Probably Won’t Need
Chemotherapy and/or radiation are not appropriate for use in GIST, although radiation may be used to control bleeding from a GIST tumor.
What Happens if the Cancer Spreads?
For some people diagnosed with GIST, the disease has already metastasized at the time of initial diagnosis. Metastasis is defined as tumor spread outside of the primary tumor site. If GIST comes back after treatment at its original site, it is known as local recurrence. Metastatic disease cannot be removed surgically, but a localized recurrence may be able to be surgically removed.
“Between 10% and 20% of GIST patients have disease that’s spread right from the start,” says Demetri. “That’s frightening, but the good news is that Gleevec is very effective in controlling metastatic GIST. It works in about nine out of 10 patients and keeps the disease under control for an average of about 2 years. But about 17% of our patients with metastatic disease who were in the initial trial that we did of Gleevec to treat GIST are still alive and taking the drug today, 12 years later,” he says.
GIST that has metastasized to the liver is sometimes also treated with a procedure called hepatic artery embolization. “If the tumor is deep in the liver where a surgeon can’t take it out without risking the blood supply to that organ, for example, surgeons might use embolization to decrease blood flow to the tumor,” Demetri says.
“In well over half of cases, GIST is either completely controlled with surgery alone, or with surgery and Gleevec to prevent recurrence,” says Demetri.