Gastrointestinal Stromal Tumors (GISTs) of the Colon and Rectum: Clinicopathological Analysis

Kim, Eun Kyu; Lee, Ho Chang; Lee, Min Ro; Lim, Seok Byung; Kang, Sung Bum; Park, Kyu Joo; Kim, Woo Ho; Park, Jae Gahb

Abstract

PURPOSE: This study was undertaken to investigate the clinicopathological features of GISTs (gastrointestinal stromal tumors) of the colon and rectum. Method: At Seoul National University Hospital from Jan. 1994 to Dec. 2002, 11 patients were diagnosed as having GISTs, leiomyomas, or leiomyosarcomas of the colon and rectum. For those 11 patients, immunohistochemical staining for CD117 (c-kit) was undertaken in order to differentiate true GISTs from leiomyomas and leiomyosarcomas. Ten patients were positive for CD117 (c-kit) and were finally diagnosed as having GISTs. Then, we retrospectively analyzed the clinical and the pathological features of those 10 cases and investigated the recurrence of disease and the survival.
RESULTS
Colorectal GISTs accounted for 0.3% of all colorectal malignancies (10 cases/2,964 cases). The male- female ratio for the 10 patients with GISTs was 8:2, and the median age was 56.5 (34~75) years. The locations of the tumor were the rectum in 9 cases (90%) and the ascending colon in 1 case. The most common symptoms were decreased stool caliber and GI bleeding (3 cases, respectively). A curative-intent resection was possible in 8 cases. There were two cases of recurrence after curative resection (25.0%). The median survival period of the 10 patients was 33.5 (2~70) months. The median tumor size was 7.5 (5~20) cm, and the median number of mitosis per 50 high-power fields was 36.5 (8~123). There was a statistically significant correlation between size and mitotic count (r=0.942, P=0.001).
CONCLUSIONS
Colorectal GISTs are very rare disease entities (0.3% of the colorectal malignancies). However, all colorectal GISTs were classified as malignant based on their sizes and mitotic counts in our study. For introduction of STI-571 in the treatment of colorectal GISTs and for further study, accurate diagnosis of GISTs by special immunohistochemical staining (c-kit) is very important in differential diagnosis of primary gastrointestinal mesenchymal tumors and recurred leiomyosarcomas.