Cancers of the Intestine, Liver, and Biliary Tract

Colorectal cancer is an important cancer worldwide, whose etiology is not fully understood. Known causes include several genetic factors, overweight/obesity, tobacco smoking, and heavy alcohol drinking. An etiologic role of diet is highly plausible, but the evidence for specific factors, with the possible exception of processed meat, is not conclusive. Workers exposed to asbestos have been found at increased risk of colorectal cancer in several studies, but the evidence is not sufficiently strong to conclude in favor of a causal association. No other occupational factors have been linked to colorectal cancer. Liver cancer is a common cancer in many regions of the world and is the second cause of cancer-specific mortality. About 75 % of liver cancers are hepatocellular carcinoma (HCC), the second most frequent type being cholangiocarcinoma (CCA). HCC develops in the context of a web of interactions between viral (HBV, HCV), environmental (alcohol, aflatoxin), and metabolic (fatty liver disease, obesity) factors. Genetic predisposition accounts for only a small fraction of the global burden of HCC. The only established occupational cause of liver cancer is vinyl chloride, which causes a rare type of neoplasm, angiosarcoma, and has also been associated with HCC. Detection and diagnosis of HCC are complicated by its occurrence in a background of chronic liver disease characterized by inflammation and cycles of hepatocyte proliferation and destruction. Markers used in clinical practice include serological and molecular markers of viral hepatitis, enzymatic tests for liver function and injury, and a growing list of plasma-based tumor markers, the current gold standard being alpha-fetoprotein (AFP). Recent research has identified molecular changes in transcriptome, microRNAome, epigenome, and, significantly, plasma proteome that pave the way to the development of a new generation of biomarkers for early detection of HCC in different etiologic contexts.