Imatinib therapy for a patient with metastasis of colonic gastrointestinal stromal tumor: report of a case

Management of rectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. However, rectal GIST is rare, the incident rate of it is approximately 5% of all GISTs. Rectal GIST symptoms generally include bleeding and/or pain and occasionally, urinary symptoms. Immunohistochemical evaluation finds that most rectal GIST tumors are CD117 (KIT) positive, and are sometimes CD34, platelet-derived growth factor receptor alpha (PDGFRA), smooth muscle actin, S-100, or vimentin positive. The National Institutes of Health (NIH) classifies rectal GIST as very-low risk, low risk, intermediate risk, or high risk, and the frequencies have been estimated as 0-23.8% for very-low risk, 0-45% for low risk, 0-34% for intermediate risk, and 21-100% for high risk tumors. The first-line treatment for localized GIST is curative resection, but is difficult in rectal GIST because of anatomical characteristics such as the deep, narrow pelvis and proximity to the sphincter muscle or other organs. Several studies noted the efficacy of the minimally invasive surgery, such as trans-anal, trans-sacral, trans-vaginal resection, or laparoscopic resection. The appropriate surgical procedure should be selected depending on the case. Imatinib mesylate (IM) is indicated as first-line treatment of metastatic or unresectable GIST, and clinical outcomes are correlated with KIT mutation genotype. However, the KIT mutation genotypes in rectal GIST are not well known. In this review, as in other GISTs, a large proportion (59-100%) of rectal GISTs carry exon 11 mutations. Although curative resection is indicated for localized rectal GIST, a high rate of local recurrence is a problem. Multimodal therapy including perioperative IM may improve postoperative outcomes, contributing to anus-preserving surgery. Moreover, KIT mutation analysis before IM treatment is important. This review summarizes current treatment strategies for rectal GIST.

Clinicopathological features and prognosis of colonic gastrointestinal stromal tumors: evaluation of a pooled case series

Background

Due to the extremely rare incidence, data about colonic GISTs are limited. Therefore, aim of the present study was to explore clinicopathological characteristics and prognosis of colonic GISTs.

Patients and Methods

Colonic GISTs cases were obtained from our center and from case report and clinical studies extracted from MEDLINE. Clinicopathological features and survivals were analyzed.

Results

There were 79 colonic GISTs patients with a female predominance. The median age was 66 years (range 0.17-84). The median tumor size was 5.8 cm (range 0.5-29). The most common location was sigmoid colon (45.8%), followed by transverse colon (19.5%). The majority of colonic GISTs were high risk (70.8%). Mitotic index was correlated with gender (P = 0.002) and tumor size (P = 0.005), and tumor location was correlated with age (P = 0.017). The five year DFS and DSS were 57.4% and 61.6%, respectively. Mitotic index and NIH risk classification were associated with prognosis of colonic GISTs. However, mitotic index was the only independent risk factor. The distribution of tumor size and NIH risk classification were significantly different between colonic and gastric GISTs (both P = 0.000). The DFS and DSS of colonic GISTs were significantly lower than that of gastric GISTs (P = 0.012 and P = 0.002, respectively).

Conclusions

The most common location for colonic GISTs was sigmoid colon. Most tumors were high risk. Mitotic index was the only independent risk factor for prognosis of colonic GISTs. Colonic GISTs differ significantly from gastric GISTs in respect to clinicopathological features. The prognosis of colonic GISTs was worse than that of gastric GISTs.

Safety of Regular-Dose Imatinib Therapy in Patients with Gastrointestinal Stromal Tumors Undergoing Dialysis

The number of cancer patients undergoing dialysis has been increasing, and the number of these patients on chemotherapy is also increasing. Imatinib is an effective and safe therapy for KIT-positive gastrointestinal stromal tumors (GIST), but the efficacy and safety of imatinib in dialysis patients remain unclear. Because clinical trials have not been conducted in this population, more investigations are required. We report on a 75-year-old Japanese man undergoing dialysis who presented with massive tarry stool from a duodenal GIST. The duodenal GIST was 14 cm in diameter with multiple liver and bone metastases. The patient underwent an urgent pancreaticoduodenectomy to achieve hemostasis. After surgery, he was administered imatinib 400 mg/day. No severe adverse event including myelosuppression, congestive heart failure, liver functional impairment, intestinal pneumonia, or Steven-Johnson syndrome occurred, and the liver metastasis remained stable for 4 months. During chemotherapy, hemodialysis continued three times per week without adverse events. We suggest that regular-dose imatinib is an effective and safe treatment in patients with GIST undergoing dialysis. In addition, we present a literature review of the effectiveness and safety of imatinib treatment in dialysis patients.