Clinicopathological characteristics and prognosis of patients with small intestinal stromal tumors.
OBJECTIVE
Gastrointestinal stromal tumors (GISTs) involving the small intestine are less common than those involving the stomach, and data on small intestinal stromal tumors (SISTs) are more limited. This study investigated the clinicopathological characteristics and prognostic factors of SISTs and compared them with those of gastric stromal tumors (GSTs).


METHODS
A total of 82 surgically resected and pathologically diagnosed smooth muscle tumors of small bowel in patients treated from January 1986 to December 2000 were included. Immunohistochemical studies were performed on these tumors with antibodies of CD117, CD34, smooth muscle actin (SMA), desmin and S-100. The results were analyzed and compared with 74 cases of GSTs diagnosed and treated from January 1986 to December 1997.


RESULTS
Among the 82 small intestine tumors, 71 were CD117-positive (86.6%) and were classified as SISTs. Of the 71 SISTs, 70.4% were immunoreactive to CD34, 88.7% to SMA, 46.5% to S-100, but none to desmin. Survival analysis demonstrated that tumor size < 5 cm (p = 0.021), mitosis number < 5/50 high-power field (p < 0.001), SMA-positive (p = 0.027), non-epithelioid cell type (p = 0.005) and tumor with skeinoid fibers (p = 0.010) predicted longer disease-free survival after operation. Multivariate analysis revealed that mitotic number (p = 0.001), cell morphology (p = 0.031) and tumor size (p = 0.004) were independent prognostic factors. In comparison to GSTs, SISTs exhibited significantly lower rates of CD34, but significantly higher rates of SMA and S-100 immunoreactivity.


CONCLUSIONS
SISTs exhibited a different immunophenotype from GSTs. SMA reactivity is a predictor of benign clinical behavior in SISTs. Tumor mitotic numbers, tumor size, and cell type were independent prognostic factors for patients with SISTs after operation.
Chiu
Yi-Chun
YC
Division of Gastroenterology, Department of Internal Medicine, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Niao-Sung Hsiang, Taiwan.
Lin
Jui-Wei
JW
Changchien
Chi-Sin
CS
Huang
Chao-Chen
CC
Liu
Shang-Yun
SY
Yi
Li-Na
LN
Chiu
King-Wah
KW
Wu
Keng-Liang
KL
Chen
Yen-Yang
YY
Chou
Fong-Fu
FF
Hu
Tsung-Hui
TH
D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000473:pathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007421:Intestine, Small; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D018709:Statistics, Nonparametric; D016019:Survival Analysis