Gastrointestinal stromal tumors (GISTs) are relatively rare cancers that originate in the cells of Cajal, which are specialized cells lining the digestive tract responsible for initiating the rhythmic movement that propels food and solid waste through the GI tract.
GISTs are characterized by specific genetic abnormalities that cause overactivity of a specific gene, called the c-kit protooncogene, and overproduction of certain proteins. Together, these abnormalities lead to uncontrolled growth and limited cell death among malignant GIST cells.
GISTs may be cancerous (malignant) or noncancerous (benign). Malignant GISTs can occur in any part of the gastrointestinal tract—from the esophagus to the rectum—but occur most commonly in the stomach and small intestine. GISTs of the stomach wall are considered malignant when they exceed 5 to 10 centimeters, have a high rate of cell division, or have metastasized (spread). GISTs of the small bowel are considered malignant if they have any mitoses or are greater than 2 centimeters.
GISTs may spread to distant sites in the body, mainly the peritoneal cavity and the liver. Location of metastatic tumors can be determined through PET (positron emission tomography) or gadolinium-enhanced magnetic resonance imaging (MRI). Diagnosis is often made surgically or by needle biopsy with the assistance of imaging to guide the needle to the tumor.
Until the development of targeted therapy, there was no effective systemic treatment for this tumor, and the prognosis for patients with recurrent local disease or metastatic disease was poor.
The following is a general overview of treatment for GISTs. Cancer treatment may consist of surgery, targeted therapy, or a combination of these treatment techniques. Combining two or more of these treatment techniques—called multi-modality care—has become an important approach for increasing a patient’s chance of cure and prolonging survival.
Participation in a clinical trial utilizing new, innovative therapies also provides promising treatment.
Circumstances unique to each patient’s situation influence which treatment or treatments are utilized. The potential benefits of multi-modality care, participation in a clinical trial, or standard treatment must be carefully balanced with the potential risks. The information on this Web site is intended to help educate patients about their treatment options and to facilitate a mutual or shared decision-making process with their treating cancer physician.
Patients with an advanced GIST have an average survival of 9 to 20 months following standard treatment. These are relatively rare tumors and in order to improve treatment, virtually all patients with this disease need to be enrolled in clinical trials.
Surgery may be used as initial therapy to completely remove the primary tumor and may also be used to remove metastatic tumors. Patients with more advanced disease may undergo targeted therapy followed by surgery once they have responded to treatment. This approach may allow some patients who were initially diagnosed with inoperable disease to undergo surgery once their cancer has responded to the targeted therapy.
Surgery as initial treatment: An evaluation of surgery for 33 patients with GIST, two-thirds of which had high-grade tumors, has shown that these cancers can be completely removed with surgery in the majority of patients. Approximately eight out of ten patients were able to have their cancer completely removed with surgery; this included some patients with metastatic disease. On average, patients survived 2.5 years. The researchers estimated that nearly half of the patients would survive more than 2.5 years. Outcomes were less favorable among patients with cancer that was not completely removed.
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