Gastrointestinal cancers are among the most common causes of cancerrelated
death in the world. Alone the subgroup of colorectal cancer is the third most
common cancer in men (746,000 new diagnosed cases in 2012, 10.0% of all cancer
cases) and the second in women (614,000 new diagnosed cases in 2012, 9.2% of all
cancer cases) worldwide. Beside different treatment strategies including surgery,
radiotherapy and/or chemotherapy have improved the survival of patients in the last
years, there is still an urgent need to improve prognosis in advanced disease by means
of targeted therapies as well as an early detection of development of acquired
resistance. For this purpose, molecular biomarkers are a promising option especially in
the light of increasing amount of personalized medicine.
In this chapter, we will review classic biomarkers for prognosis already in clinical use
(e.g. carcinoembriogenic antigen, cancer antigen 19-9, serum pepsinogen I, α-
fetoprotein, CD117) and new ones with their usefulness following combined
therapeutic regimens. Some new technologies like the very sensitive digital-drople-
-PCR, next-generation sequencing and high-throughput screening methods for RNA
expression patterns will be discussed shortly regarding their application for detecting
and discovering potential new biomarkers. Finally, possible new potential mechanisms
of resistance related to targeted pathways will be discussed as genetic and epigenetic
alterations (hypermethylation of CpG-islands, copy-number variation, lncRNAs and
single nucleotide polymorphisms). Furthermore, the potential of circulating tumour
DNA and non-coding RNAs, with a special focus on microRNAs as new biomarkers
will be addressed.
Keywords: α-fetoprotein, Anal cancer, Billary tract cancer, Biomarker, CA19-9,
CD117, CEA, Cft-DNA, Cholangiocarcinoma, Colorectal cancer, Digital-droplet
PCR, Gallbladder cancer, Gastric cancer, Gastrointestinal cancer, Liver cancer,
Liquid biopsy, lncRNA, Microarrays, MicroRNA, Microsatellite instability,
NanoString, Next-generation sequencing, Oesophagus cancer, Pancreatic cancer,
SEPT9, Serum pepsinogen I, Small intestine cancer, TAG72, TPS.