What You Need to Know About GIST
A subsequent study was performed using Gleevec for either three years or one year. The three-year duration was superior to the one-year duration. The three-year duration for adjuvant imatinib has been approved by the FDA, for routine use after surgery for intermediate to high-risk GIST.
“It’s clearly been shown that Gleevec can reduce the risk of GIST recurrence, and in high-risk patients, it even improves their overall survival rates,” says Khushalani.
For individuals with the PDGFRA mutation, Gleevec is not recommended. The presence of this gene mutation results in imatinib resistance, but also results in a reduced risk of recurrent GIST.
What if the Cancer Has Spread?
In 15% of cases, GIST cannot be completely removed with surgery. In this case, Gleevec has been used prior to surgery, to attempt to shrink the tumor and make surgery possible. This therapy, known as neo-adjuvant therapy, was found to be safe and effective and therefore should be used on a case-by-case basis. However, if the tumor still remains unable to be surgically removed, imatinib should be continued after surgery.
“Depending on the size of the tumor or where it is located, we might not be able to get it all -- at least not without doing real damage to the person’s ability to function,” says Demetri. For example, taking out a large tumor at the end of the stomach, where it empties into the duodenum, could so damage your digestive system that you might never be able to eat or eliminate waste normally.
For a few people who are diagnosed with GIST, the disease has already metastasized, meaning that it has spread beyond the area where it started in the digestive system and into other places in the body.
Metastatic GIST is disease that has spread outside of the site of origin of the primary tumor. This disease cannot be removed surgically. In these cases, the use of imatinib is the treatment of choice. Response rates and disease stability are approximate 90%. Long-term survival (9 years) is 35%.
“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.