Management of rectal gastrointestinal stromal tumor

Abstract

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 mutation genotype. However, the 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, mutation analysis before IM treatment is important. This review summarizes current treatment strategies for rectal GIST.

Frequent rectal gastrointestinal stromal tumor recurrences in the imatinib era: Retrospective analysis of an International Patient Registry

“…In accordance with other reports, the vast majority of mutations were in exon 11 . We also found similar proportions of rarer mutations, such in exons 9 and 13 . While this is one of the largest groups of rectal GIST patients with documented mutations, it still only represents a little over half of the cohort.…”

“…While the prevalence of driver mutations in KIT is estimated to be around 75% in the general GIST population, it appears to be higher in rectal GIST population . In accordance with other reports, the vast majority of mutations were in exon 11 . We also found similar proportions of rarer mutations, such in exons 9 and 13 .…”

The Role of Magnetic Resonance Imaging in the Differential Diagnosis of Giant Rectal and Perirectal Masses

“…Giant tumors located in the rectal and perirectal regions cause compression and distortion in normal anatomic structures, so it may be difficult to determine the origin of the tumor and decide the correct diagnosis and treatment (1)(2)(3)(4)(5)(6). Masses such as rectal adenocarcinoma, sarcoma, neuroendocrine tumor, leiomyoma, ovarian mass, rectal gastrointestinal stromal tumor (GIST), prostate adenocarcinoma, lymphoma, neurogenic tumor and congenital cyst should be considered in the differential diagnosis of giant rectal and perirectal tumors (6). Although rectoscopy-guided biopsy is the most important method for diagnosis, it is insufficient to evaluate intramural and extramural extension of the mass (1,5).…”

“…Although rectoscopy-guided biopsy is the most important method for diagnosis, it is insufficient to evaluate intramural and extramural extension of the mass (1,5). Pre-operative imaging is necessary to determine the location of the mass (submucosal/intramural/extramural) and its extension, to evaluate the need for surgical approach to the patient and to decide the surgical technique to be applied (1)(2)(3)(4)(5)(6)(7). Computed tomography (CT) and magnetic resonance imaging (MRI) are used in the diagnosis and evaluation of rectal and perirectal tumors (1)(2)(3)(4)(5)(6)(7).…”

“…Pre-operative imaging is necessary to determine the location of the mass (submucosal/intramural/extramural) and its extension, to evaluate the need for surgical approach to the patient and to decide the surgical technique to be applied (1)(2)(3)(4)(5)(6)(7). Computed tomography (CT) and magnetic resonance imaging (MRI) are used in the diagnosis and evaluation of rectal and perirectal tumors (1)(2)(3)(4)(5)(6)(7). MRI is more appropriate because it does not contain radiation and has high soft tissue resolution (1)(2)(3)(4)(5).…”