Treatment

Treatment of GISTs depends on the onset at the diagnosis and may be surgical or medical.

Surgical treatment
In the case of resectable disease, a surgical approach remains the gold standard. It is hoped that a complete resection of the tumor - with negative resection margins - is obtained. Surgical techniques depend on the site of origin and size of the neoplasm. In case of small tumors and accessible sites, limited resections can be achieved by a laparoscopic approach, while in the case of large tumors and inaccessible sites, demolition surgery must be performed. There are few data on the efficacy of surgery in cases of relapses or metastatic disease.

Medical treatment
In the case of unresectable disease, a treatment with imatinib (Glivec) is advised. Imatinib is a molecular drug that inhibits many thyrosine kinases of receptors, such as KIT and PDGFr alfa. It is orally administered at the initial dose of 400 mg/day and this treatment must be continued until progression of the disease or drug intolerance. After progression of the disease, a dose increase to 800 mg/day is advised. The treatment is generally well tolerated and side effects are usually mild, such as periorbital edema, nausea, diarrhea, musculoskeletal pain, fatigue, dermatitis or skin rash. Serious side effects are observed only in 5% of patients.
After a good response to imatinib, the majority of patients usually develop secondary resistance to drug and tumor progression. For this reason, it is necessary to use other drugs with specific molecular targets, such as sunitinib (Sutent). This molecule primarly inhibits tyrosine kinases involved in the patogenesis of GIST (KIT and PDGFR alfa) and, additionally, it inhibits neoangiogenesis.
In the case of disease progression or intolerance during imatinib administration, a treatment with sunitinib at 37,5 mg/day is now indicated and it must be continued until new progression of disease or intolerance. Clinical trials based on new tyrosin kinase and angiogenesis inhibitors are currently ongoing in Italy with the purpose to find new medical treatments for progressive disease.