The True Incidence of Gastric GIST: an Update

Rare c-KIT c.1926delA and c.1936T>G Mutations in Exon 13 Define Imatinib Resistance in Gastrointestinal Stromal Tumors and Melanoma Patients: Case Reports and Cell Experiments

Background: Target therapies play more and more important roles in gastrointestinal stromal tumors (GISTs) and melanoma with the advancement of clinical drugs that overcome the resistance caused by gene mutations. c-KIT gene mutations account for a large portion of GIST patients, which are known to be sensitive or resistant to tyrosine kinase inhibitors. However, the role rare mutations play in drug efficacy and progression-free duration remains elusive.

Methods: Two rare mutations were identified using Sanger sequencing from the GIST and melanoma cases. Cell experiments were further carried out to demonstrate their role in the imatinib resistance.

Results:c-KIT c.1926delA p.K642S*FS mutation in primary and recurrent GIST patients and c-KIT c.1936T>G p.Y646D point mutation in melanoma patients in exon 13 were first demonstrated to be novel targets resistant to imatinib agent.

Conclusion:c-KIT mutations c.1926delA and c.1936T>G in exon 13 are clinically significant targets that exhibit resistance to imatinib. This study provides guidance to GIST and melanoma treatments.

Gastrointestinal Stromal Tumors (GISTs) as Incidental Findings in Gynecological Surgery

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract that may be diagnosed incidentally as a part of intra-abdominal surgery for other diseases. This is a single center review to document the incidental finding of GIST at surgery for gynecological malignancies during a 10-yr period. Sixteen cases of incidental GISTs were identified in women ranging in age from 39 to 82 yr. GISTs presented as incidental secondary lesions in women undergoing surgery for other indications, typically primary debulking surgery for tubo-ovarian high-grade serous carcinoma. The GIST was located in the stomach wall in 9 cases. Other sites were cecum, omentum, and mesentery. Diagnosis of GIST was supported by immunohistochemistry in all cases and by molecular studies in 3 cases. Seventy-five percent of cases were micro-GISTs, measuring <2 cm in diameter and, where Miettinen and Lasota criteria could be applied, fitted into "no risk," "very low risk" or "low risk" prognostic groups. Seventy-five percent of women for whom survival data was available, showed disease-free survival at follow-up. The 2 women who died had concurrent high stage or high-grade gynecological malignancy at initial diagnosis.

The Incidence of Gastrointestinal Stromal Tumors in Obese Patients—A Large Single Center Experience

Background and Objectives: Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms located mainly in the fundus (60–70%). The incidence of GIST is approximately 10 per million population per year in Europe, with a peak incidence at the age of 63. Recent studies suggest that morbidly obese patients have a higher incidence of GIST than the general population. The aim of this study was to analyze the incidence of GIST in patients undergoing laparoscopic sleeve gastrectomy (LSG) in our department. Materials and Methods: this paper present the retrospective study of prospectively collected data of 1564 patients who underwent LSG in a single large bariatric center from October 2013 to September 2021. After surgery, each sample of the resected stomach was sent for histopathological examination. For the analysis, we included patients diagnosed with GIST intraoperatively or postoperatively. Results: GISTs were found in five patients (0.31%). There were three men and two women. The mean age was 50.2 (range 32–63 ± 11.8) and the mean preoperative body mass index was 43.3 kg/m² (40–49.4 ± 3.2). In four cases, GISTs were found in the fundus (80%), and in one in the pylorus (20%). None of the tumors were larger than 7 mm in diameter and all were diagnosed as a very low-risk category. No adjuvant treatment was required. All patients achieved good or satisfactory bariatric and metabolic results. Conclusions: The incidence of GIST in our study was estimated at 0.31%. All patients had a very low-risk GIST and no recurrence until follow-up. Recent literature suggests that the risk of GIST is higher in the obese population, and therefore surgeons should be aware of the risk of incidental GIST during LSG.

Gastro-Intestinal Tract Cancers Following Bariatric Surgery: a Narrative Review

The association between obesity and malignancies has been identified epidemiologically. Meanwhile, the increasing global number of bariatric surgeries is reported annually; bariatric surgery's effect on different types of cancers is not well understood. Unfortunately, nonspecific presentations and difficulties regarding investigations make diagnosis challenging. The aim of this study is to compile available data about gastro-intestinal (GI) cancers, occurring after different bariatric surgeries. Although GI cancers are considered a rare complication of obesity surgery, they do exist, and diagnosis needs a high index of suspicion.