Cancer of the colon or rectum is known as colorectal cancer because they both share some common features. The colon is often known as the big intestine or large bowel. The rectum is a tube that runs from the colon to the anus. 

The majority of colon cancers are caused by polyps, which are growths within the colon's inner lining. The likelihood of a polyp turning malignant is determined by factors such as the type of polyp (adenomatous polyps are considered precancerous) and if it contains abnormal cells (called dysplasia).

Chromosomal instability, CpG island methylator phenotype, and microsatellite instability all play a role in colorectal cancer. Aneuploidy and loss of heterozygosity are the most common causes of genetic instability. Cellular transformation can also be caused by mutations in tumor suppressors or cell cycle genes. Microsatellite instability and the mutator phenotype can also be caused by epigenetic and/or genetic changes that result in compromised cellular mechanisms, such as the DNA repair system. Non-coding RNAs, particularly microRNAs and long non-coding RNAs, have also been linked to different phases of Colorectal cancer.

In terms of risk factors, a person's risk of having colon cancer rises with age, particularly beyond the age of 50. Furthermore, having type 2 diabetes, inflammatory bowel disease (for example, ulcerative colitis), or a family history of colorectal cancer, as well as other modifiable risk factors including being overweight and eating a diet high in fat, raises a person's risk of developing colorectal cancer.

However, colonoscopy and other forms of screening along with the right treatment are required to survive colorectal cancer. Unfortunately, advanced colorectal cancer patients have a substantially lower five-year survival rate. Surgery, radiation, chemotherapy, or embolization may be used depending on the stage and spread of colorectal cancer.