Gastrointestinal stromal tumor: 15-years' experience in a single center

Abstract

Background: Gastrointestinal stromal tumor (GIST) is known for its wide variability in biological behaviors and it is difficult to predict its malignant potential. The aim of this study is to explore the characteristics and prognostic factors of GIST.

Methods: Clinical and pathological data of 497 GIST patients in our center between 1997 and 2012 were reviewed.

Results: Patients were categorized into very low-, low-, intermediate- and high-risk groups according to modified National Institutes of Health (NIH) consensus classification system. Among the 401 patients untreated with imatinib mesylate (IM), 5-year overall survival (OS) in very low-, low-, intermediate- and high-risk groups was 100%, 100%, 89.6% and 65.9%; and 5-year relapse-free survival (RFS) was 100%, 98.1%, 90.9% and 44.5%, respectively. Univariate analysis revealed that sex, tumor size, mitotic rate, risk grade, CD34 expression, and adjacent involvement were predictors of OS or RFS. COX hazard proportional model (Forward LR) showed that large tumor size, high mitotic rate, and high risk grade were independent risk factors to OS, whereas high mitotic rate, high risk grade and adjacent organ involvement were independent risk factors to RFS. The intermediate-high risk patients who received IM adjuvant therapy (n = 87) had better 5-year OS and RFS than those who did not (n = 188) (94.9% vs. 72.1; 82.3% vs. 56.3%, respectively). Similarly, advanced GIST patients underwent IM therapy (n = 45) had better 3-year OS and 1-year progression-free survival (PFS) than those who didn't (n = 42) (75.6% vs. 6.8%; 87.6% vs. 12.4%, respectively).

Conclusions: Very low- and low-risk GISTs can be treated with surgery alone. Large tumor size, high mitotic rate, high risk grade, and adjacent organ involvement contribute to the poor outcome. IM therapy significantly improves the survival of intermediate-high risk or advanced GIST patients.

Figure 1

Annual number of newly admitted GIST patient since 1997.

Figure 2

Overall survival in 401 GIST patients according to risk class.

Figure 3

Relapse-free survival in 401 GIST patients according to risk class.

Figure 4

Effect of treatment with or without postoperative IM adjuvant therapy on OS and RFS in 275 intermediate-high risk GIST patients (A: overall survival; B: relapse-free survival).

Figure 5

Effect of treatment with or without post-operation IM therapy on OS and PFS in 87 advanced GIST cases (A: overall survival; B: progression-free survival).