GIST is the most common mesenchymal tumour of gastrointestinal tract arising from mutation of KIT or PDGFRA gene. Surgery is the primary method of treatment, however a targeted therapy with imatinib is necessary due to recurrence.
The aim of the study was to evaluate efficacy of the targeted chemotherapy in advanced gastrointestinal stromal tumours with non-exon 11 KIT mutations.
Material and methods. Data from 279 patients with advanced GIST treated with imatinib between 2001 and 2011 were analysed in the study. Exon 11 KIT mutation was found in 192 patients (68.7%), non-exon 11 KIT mutation was found in 87 patients (31.3%): this group included lack of mutation - wild-type, exon 9 KIT mutations, exon 18 PDGFRA D842V mutations, non-D842V PDGFRA mutations as well as non-exon 9 and 11 KIT mutations. Analysis of progression-free survival and overall survival were done for the entire group of patients and for patients with particular mutations, and then effects on progression-free survival and overall survival of such factors as sex, age, imatinib dose were evaluated.
Results. Occurrence of non-exon 11 KIT mutation increases the risk of disease progression by 20% in comparison to the presence of exon 11 KIT mutation, however it does not increase the risk of patient’s death. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation. Percentage of 5-year survivals in case of the presence of D842V PDGFRA mutation is more than twice worse than in the case of the other mutations. Lesion location in the gastrointestinal tract affected the risk of death, with the greatest percentage of 5-year survival for lesions located in the stomach. Such factors as sex, age at diagnosis (<50, ≥50 years) and imatinib dose did not affect the risk of disease progression and the risk of patient’s death.
Conclusions. The ratio of overall survival of patients with advanced GIST with a mutation other than exon 11 KIT mutation treated with imatinib is similar to the ratio of overall survival of patients with GIST with exon 11 KIT mutation. An exception is the group of patients with GIST in whom the presence of D842V PDGFRA mutation was found. In general, longer survival has been found in patients with GIST located in the stomach in comparison to the small intestine or other less frequent locations. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation.
3. Chun-Nan Yeh, Yen-Yang Chen, Jeng-Hwei Tseng et al.: Imatinib Mesylate for Patients with Recurrent or Metastatic Gastrointestinal Stromal Tumors Expressing KIT: A Decade Experience from Tajwan. Translational Oncology Volume 4 Number 6 December 2011; pp. 328-35.
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