Colorectal cancer is one of the most common cancer types worldwide. Since colorectal
cancer takes time to develop, its incidence and mortality can be treated effectively if it is detected
in its early stages. As a result, non-invasive or invasive biomarkers play an essential role in the early diagnosis of colorectal cancer. Many experimental studies have been carried out to assess genetic, epigenetic, or protein markers in feces, serum, and tissue. It may be possible to find biomarkers
that will help with the diagnosis of colorectal cancer by identifying the genes, RNAs, and/or proteins indicative of cancer growth. Recent advancements in the molecular subtypes of colorectal
cancer, DNA methylation, microRNAs, long noncoding RNAs, exosomes, and their involvement
in colorectal cancer have led to the discovery of numerous new colorectal cancer biomarkers. In
small-scale investigations, most biomarkers appear promising. However, large-scale clinical trials
are required to validate their effectiveness before routine clinical implementation. Hence, this review focuses on small-scale investigations and results of big data analysis that may provide an
overview of the biomarkers for the diagnosis, therapy, and prognosis of colorectal cancer.