Objective: To analyze the outcome of 200 patients with gastrointestinal stromal tumor (GIST) who were treated at a single institution and followed up prospectively.
Summary Background Data: A GIST is a visceral sarcoma that arises from the gastrointestinal tract. Surgical resection is the mainstay of treatment because adjuvant therapy is unproven.
Methods: Two hundred patients with malignant GIST were admitted and treated at Memorial Hospital during the past 16 years. Patient, tumor, and treatment variables were analyzed to identify patterns of tumor recurrence and factors that predict survival.
Results: Of the 200 patients, 46% had primary disease without metastasis, 47% had metastasis, and 7% had isolated local recurrence. In patients with primary disease who underwent complete resection of gross disease (n = 80), the 5-year actuarial survival rate was 54%, and survival was predicted by tumor size but not microscopic margins of resection. Recurrence of disease after resection was predominantly intraabdominal and involved the original tumor site, peritoneum, and liver.
Conclusions: GISTs are uncommon sarcomas. Tumor size predicts disease-specific survival in patients with primary disease who undergo complete gross resection. Tumor recurrence tends to be intraabdominal. Investigational protocols are indicated to reduce the rate of recurrence after resection and to improve the outcome for patients with GIST.
Gastrointestinal stromal tumor (GIST) is an uncommon visceral sarcoma that arises predominantly in the gastrointestinal tract. During the past three decades, there has been considerable debate regarding its nomenclature, cellular origin, diagnosis, and prognosis. 1 Due to their similar appearance by light microscopy, GISTs were previously thought to be smooth muscle neoplasms, and most were classified as leiomyosarcoma. With the advent of immunohistochemistry and electron microscopy, 2 it became apparent that GISTs may have myogenic features (smooth muscle GIST), 3 neural attributes (gastrointestinal autonomic nerve tumor), 4–6 or characteristics of both muscle and nerve (mixed GIST), or may lack differentiation (GIST not otherwise specified).
The precise cellular origin of GIST recently has been proposed to be the interstitial cell of Cajal, an intestinal pacemaker cell. 7 This postulate is supported by the finding that GISTs have cell markers similar to those of the normal Cajal cell. They stain for the myeloid stem cell antigen CD34 in 52% to 72% of cases 7,8 and are frequently marked by the presence of the c-kit protooncogene. 7,9 On ultrastructural examination, the Cajal cell has characteristics of both smooth muscle and neural differentiation. Thus, neoplastic Cajal cells could preferentially express one, both, or neither of these features, accounting for the variants of GIST.
Most of the published reports of GISTs contain few patients, span long periods, include benign mesenchymal tumors, 10,11 and do not distinguish between primary and recurrent disease. 12–14 Previously, we reported our initial experience with 38 patients with GIST. 15 In this study, we analyzed our experience of 200 patients with GIST to identify the variables predictive of survival and the patterns of disease recurrence.