Mutations
The growth and death of cells in the colon usually is carefully regulated by the body. Colon tumors, the Mayo Clinic explains, is the result of changes in cells in the colon that causes them to grow in an unregulated way. Sporadic genetic mutations can occur over time, leading to these cells developing the ability to grow abnormally. Most of the time, the American Cancer Society explains, these cells are in the lining of the intestines. Although anyone can develop these genetic changes, the Mayo Clinic explains that people with inflammatory bowel disease, people with diets that are high in fat and low in fiber and people who are not physically active enough are more likely to develop these kinds of mutations. Smoking and heavy alcohol use also can put a person at a greater risk of developing colon cancer.
Inherited Cases
Some cases of colon cancer are hereditary, the National Human Genome Research Institute (NHGRI) explains. These types of colon cancer are a result of genetic mutations that patients inherit from their parents. Two such inheritable diseases are called familial adenomatous polyposis and hereditary nonpolyposis colon cancer. Virtually all patients with familial adenomatous polyposis, according to the NHGRI, develop colon cancer by age 40. Someone with this disorder has a mutation in a gene called APC. Eighty percent of patients with hereditary nonpolyposis colon cancer develop colorectal cancer at some point. Several different genetic mutations can cause this type of colon cancer.
Progression
Most cases of colon cancer begin as small growths of abnormal cells called polyps, which are growths that have not gained the ability to invade other tissues. Medline explains that polyps are pre-cancerous, which means they are not yet cancerous but can evolve into cancer. If polyps are not removed, the cells can develop the ability to spread to other tissues, leading to colon cancer. Once colon cancer can invade other tissues, it can metastasize, which means it can spread throughout the body and form additional tumors outside the digestive system.
