Synchronous cancer is defined as the simultaneous tumor occurrence in two or more organs or places. In the gastrointestinal tract, the most common combination is gastric cancer associated with colorectal cancer. Eom et al.  reported that colorectal cancer found simultaneously with gastric cancer accounts for 20.1% of all synchronous cancers. As a result of the development of diagnostic tools and a well-organized national health insurance system, the detection of gastric cancer, combined with colorectal cancer, has increased in Korea [4,5].
GIST has been known as a submucosal tumor that can occur anywhere from the esophagus to the anus. It occurs most frequently in the stomach (70%) and small intestine (25%) . GIST is diagnosed with an endoscope or computed tomography, and although the treatment may be slightly different depending on the place or size of the tumor, the treatment of choice is surgical resection. There have been several cases in which gastric GIST was found simultaneously with gastric cancer [12,13]. In addition, the mechanism of multiple GISTs has not yet been clarified, but several studies have been reported previously [14,15]. However, to the best of our knowledge, our case is the first to be reported in which EGC with three gastric GISTs combined with synchronous colon cancer was detected.
The patient first came to our hospital for further evaluation of a simple gastric GIST. During repeated diagnostic tests, we accidentally found another gastric GIST, an EGC, and colon cancer. Finally, we detected another GIST in the stomach specimen after surgery. From the diagnosis to the treatment, various departments collaborated. A multidisciplinary approach was performed organically with the Departments of Surgery (Division of Gastrointestinal and Colorectal), Gastroenterology, Radiology, Pathology, and Nuclear Medicine. Close consultation and multidisciplinary care are important parts of modern medicine, and it is even more necessary for patients with multiple cancers. Owing to the development of video conferencing and well-designed cell phone applications, it is possible to ask the opinions of other specialists without being face-to-face.
An EGC could be removed by endoscopic submucosal dissection, and GISTs could be treated by wedge resection. However, two of the GISTs, in this case, were large and positioned in the high body of the stomach. Thus, we were concerned about complications such as a stricture. We decided to perform total gastrectomy for the lesions of the stomach. After performing lymph node dissection, we judged near-total gastrectomy would be possible, leaving a small proximal part of the stomach without esophageal transection. As a result, avoiding the high complications of anastomosis of esophagojejunostomy, the EGC was removed with a sufficient proximal margin, and the GISTs were resected completely. Subsequently, conventional colorectal surgery was performed.
In this case, all procedures were performed by laparoscopy. A long midline incision would have been inevitable if we could not proceed with the laparoscopic technique for gastrectomy and colectomy. This type of incision could lead to many complications, such as increased postoperative pain, reduced ambulation, and increased length of postoperative hospital stay . Laparoscopic surgery has recently become a popular option and has been gradually replacing conventional open surgery in several fields of abdominal surgery. The popularization of three-dimensional scopes, development of automatic linear staplers, and improvement of surgical skills of surgeons are important factors for the recent trends of laparoscopic surgery. For treating EGCs, the laparoscopic approach has become a treatment of choice according to the domestic guideline . Likewise, laparoscopic surgery is gradually expanding its indication for treating colorectal cancer .
Genetic testing may be performed when hereditary colon cancer is suspected when multiple synchronous colorectal cancers occur at the same time at a young age or when concurrent cancers occur in other organs . However, when gastric cancer and colorectal cancer occur simultaneously, both cancers usually have been found to be primary lesions. We could not find any particular genetic mutation in this case, and there are few specific genetic tests in these concurrent cancers . We experienced a rare patient with an EGC with multiple gastric GISTs combined with synchronous colon cancer. In the future, if similar cases are accumulated in several studies, it is necessary to investigate the genetic mutation tests in the case of these synchronous diseases.