Effects of synbiotics on cancer risk biomarkers

Colorectal cancer (CRC) is the fourth most common cause of death from cancer in the world and second most common (behind lung cancer) in developed countries. In recent years there has been much interest in the potential use of prebiotics, probiotics and synbiotics in the prevention and treatment of CRC. We have previously shown that synbiotic consumption in Azoxymethane treated rats modulates the immune system, influences the genotoxic potential of caecal contents and reduces the number of colonic tumours compared to control rats who did not receive the synbiotic. The aim of the current study was to identify biomarkers suitable for use as cancer risk markers and as intervention markers. A second aim was to determine the influence of synbiotic consumption on cancer risk biomarkers such as in vivo colonic mucosal proliferation and genotoxic damage along with examining the genotoxic, cytotoxic and tumour promoting potential of faecal water (FW). Synbiotic consumption altered the composition of the gastrointestinal flora and reduced in vivo genotoxic damage and the genotoxic potential of FW in cancer and polyp subjects. Synbiotic consumption also reduced the proliferative activity in the colonic mucosa in polyp subjects. In both cancer and polyp subjects gene expression in the colonic mucosa was modulated in synbiotic consuming subjects. In this and other studies the activity of natural killer cells, the level of PGE2 in FW, IL-12 production by PBMCs, genotoxic damage in the colonic mucosa and the tumour promoting activities of FW have been identified as possible biomarkers of cancer risk. Future large scale studies investigating these parameters in healthy and diseased individuals are needed to confirm the suitability of these markers in assessing cancer risk and the role of synbiotics in modulating them.

The use of PET-CT in the assessment of patients with colorectal carcinoma.

Colorectal cancer is the third most commonly diagnosed cancer, accounting for 53,219 deaths in 2007 and an estimated 146,970 new cases in the USA during 2009. The combination of FDG PET and CT has proven to be of great benefit for the assessment of colorectal cancer. This is most evident in the detection of occult metastases, particularly intra- or extrahepatic sites of disease, that would preclude a curative procedure or in the detection of local recurrence. FDG PET is generally not used for the diagnosis of colorectal cancer although there are circumstances where PET-CT may make the initial diagnosis, particularly with its more widespread use. In addition, precancerous adenomatous polyps can also be detected incidentally on whole-body images performed for other indications; sensitivity increases with increasing polyp size. False-negative FDG PET findings have been reported with mucinous adenocarcinoma, and false-positive findings have been reported due to inflammatory conditions such as diverticulitis, colitis, and postoperative scarring. Therefore, detailed evaluation of the CT component of a PET/CT exam, including assessment of the entire colon, is essential.