Giant malignant gastrointestinal stromal tumors: Recurrence and effects of treatment with STI-571

AIM: Malignant gastrointestinal stromal tumors (GISTs)are rare. Tumors larger than 10 cm tend to recur earlier:the larger the volume of the tumor, the worse the prognosis.We hypothesized that treatment with imatinib mesylate (Gleevec; STI-571), a c-kittyrosine kinase inhibitor, as palliative therapy would prolong the survival of patients with recurrent giant malignant GISTs after resection.METHODS: We performed a retrospective analysis of the effects of resection on patients with giant GISTs (＞10 cm in diameter) to determine the overall survival and recurrence rates. Twenty-three patients diagnosed with giant GISTs were included from June 1996 to December 2003. STI571 was not available until January 2000. After that time,9 patients received this drug. The factors of age, sex, tumor location, histological surgical margin, and STI-571, tumor size changes and drug side effects were reviewed. We compared the survival rate to determine the prognostic factors and the effects of STI-571 on patients with recurrent malignant gastrointestinal stromal tumor.RESULTS: The positive surgical margin group had a significantly higher recurrence rate than the negative margin group (P = 0.012). A negative surgical margin and palliative treatment with STI-571 were significant prognostic variables (Log-rank test,P＜0.05). Age, sex and tumor location were not significant prognostic variables. The 5-year survival rate of the surgical margin free patients was 80%and the 2-year survival rate of the surgical margin positive patients was 28%. The 5-year survival rate was 80% for the patients given STI-571 and 30% for the patients not given STI-571. The use of STI-571 gave a significant tumor shrinkage (6/9) rate in patients with giant GIST recurrence after resection.CONCLUSION: A negative surgical margin and the use of STI-571 after surgical resection were good prognostic indicators. Achieving a tumor-free surgical margin is still the best primary treatment for patients with such tumors.If STI-571 is used immediately when the surgical margin is positive and the tumor recurs after resection, then the prognosis of patients with giant GISTs can be improved.

Helical CT findings and clinicopathologic features in malignant gastrointestinal stromal tumors: the correlation between radiologic appearance and malignant potential

Objective： In this pictorial essay, we described the clinical, pathologic, and computed tomographic （CT） findings of malignant gastrointestinal stromal tumors （MGISTs） and attempt to establish the correlation between radiologic appearance and malignant potential. Methods： This retrospective analysis included 20 patients receiving treatment for MGIST between 2008 and 2010. The diagnosis was established by pathology and immunohistochemistry. All these patients underwent pre- operative CT. Clinical presentation, pathology and CT images were analyzed. Helical CT images were reviewed for morpho- logic features such as tumor size, number and location, tumor margins, necrosis, degree of enhancement and metastasis. Results： Gastrointestinal bleeding, abdominal pain and discomfort, and without clinical symptom were common findings and were observed in 9 （45%）, 6 （30%）, and 5 （25%） of the 20 patients. 8 （40%） tumors were located in stomach, and 10 （50%）, 1 （5%） and 1 （5%） were located in small intestine, mesentery and peritoneum, respectively. Male to female ratio was about 1：2. The size of MGIST ranged from 2.6 cm to 17.5 cm with a mean of 8.7 cm. All tumors density was inhomogeneous and heterogeneous enhancement. MGISTs with highly malignant located in small intestine were about 30% higher than stomach. The ＂satellite＂ turnouts were found in 6 cases with high malignant risk. 7 cases were suffered from liver metastasis, and 4 cases went with seeding into the abdominal cavity, 1 cases went with lymph node metastasis. Histologically, 19 cases （95%） were of spindle cell type. Immunohistochemical stains demonstrated a strong positivity for both c-kit （CDl17） and CD34s enhancement in 19 （95%）. Conclusion： Clinical expression is varied in MGIST patients. Female might be predominance in MGIST. The GISTs located in small intestine would tend to be more aggressive. The satellite tumours, necrosis and cystic degeneration were strongly benefit for MGIST diagnosis. Furthermore, intestinal obstruction doesn＇t support the diagnosis. Lymph node metastasis and calcification is rare.

Gastrointestinal stromal tumors and second primary malignancies before and after the introduction of imatinib mesylate

Gastrointestinal stromal tumor （GIST） is the most common mesenchymal malignancy of the gastrointestinal tract.GISTs may coexist with different types of cancer,either synchronous or metachronous （1）.Most GISTs develop in a sporadic fashion,but familial occurrence,such as neurofibromatosis and Carney-triad,has also been reported （2）.The overall frequency of second tumors in different series varied from 4.5% to 33%.The most frequent types of GIST-associated cancers were gastrointestinal carcinomas （47%）,lymphoma/leukemia （7%）,carcinomas of prostate （9%）,breast （7%）,kidney （6%）,lung （5%）,female genital tract （5%）,carcinoid tumors （3%）,soft tissue and bone sarcomas （3%）,malignant melanoma （2%） and seminoma （1%） （1,3-5）.