The controversial role of in colorectal cancer.

Colorectal cancer (CRC) is a complex and widespread disease, currently ranked as the third most frequent cancer worldwide. It is well known that the gut microbiota has an essential role in the initiation and promotion of different cancer types, particularly gastrointestinal tumors. In fact, bacteria can trigger chronic inflammation of the gastric mucosal, which can induce irreversible changes to intestinal epithelial cells, thus predisposing individuals to cancer. Some bacterial strains, such as and spp. have a well established role in CRC development. However, the role of still remains controversial. While part of the literature suggests a harmful role, other papers reported as an important probiotic microorganism, with great applicability in food products. In this review we have examined the vast majority of published data about either in CRC development or concerning its protective role. Our analysis should provide some answers regarding the controversial role of in CRC.