Clinicopathological and Corresponding Genetic Features of Colorectal Signet Ring Cell Carcinoma

Europe and the United States have high morbidity rates of colorectal cancer, it being the third most common new cancer among both men and women each year. Colorectal cancer morbidity is also high in Japan. Advances in surgery, chemotherapy, and molecular targeted drugs have extended the prognosis of colorectal cancer, although the effects of these treatments remain poor in some patients. Colorectal cancer almost always presents as differentiated adenocarcinoma, although one tissue type, signet-ring cell carcinoma, occurs rarely. Overall, colorectal signet-ring cell carcinoma is very infrequent among cases of colorectal cancer, however, its prognosis is reported as being extremely poor. Several reports have addressed its clinicopathological and typical genetic characteristics, such as mutation of viral oncogene Kirsten rat sarcoma (KRAS) gene, but there have been few comprehensive investigations of its characteristics and genetic background. In this review, we examine features of colorectal signet-ring cell carcinoma by summarizing its clinical and genetic characteristics.