Synchronous colorectal adenocarcinoma and gastrointestinal stromal tumor (GIST)

Background: Little is known about the synchronous occurrence of gastrointestinal stromal tumors (GISTs) and other gastrointestinal tumors. We present two cases of an invasive colon cancer with a synchronous small-bowel GIST; immunohistochemistry studies were performed to evaluate possible genetic similarities. Methods: This paper reports two cases of synchronous GISTs and colorectal cancer (CRC) with immunohistochemistry analysis of c-Kit expression. This paper is also a review of the existing literature on the association of GISTs and CRC and the role of c-Kit in CRC. Results: In the last 2 years, we observed two patients with synchronous CRCs and GISTs of the small bowel. The GISTs were incidentally discovered during the work-up for CRCs and excised at the time of the colon resection. Immunohistochemistry study did not reveal an expression of c-Kit in CRCs. Clinical implications of the association between these two neoplasms are described in this paper. Conclusions: Synchronous CRCand GIST has been more frequently reported. Because of the limited number of cases, we cannot exclude an incidental relationship. The genetic pathways of tumorigenesis appear different for the two neoplasms. Further studies are needed to clarify a possible role of c-Kit in the development of colonic adenocarcinomas.