Types of Colorectal Cancer

Colorectal cancer is a collective term that refers to cancer of the colon and rectum. Given that cancerous growth could occur anywhere along the 6-foot-long large intestine and rectum, the growths and tumors often result in different types of cancers.

The type of cancer determines the kind of treatment a patient can receive, and with it, the chances of effective treatment and recovery vary.

While there are many ways in which colorectal cancer can occur, here are the four most common ways.

A key culprit is adenocarcinoma, which makes up 96% of colorectal cancer cases. Adeno refers to glands, while carcinoma refers to a cancer that arises in the epithelial tissue or lining of an organ.

The inner lining of the colon is made up of cells that secrete mucus to help maintain a healthy relationship between the epithelial lining and gut bacteria. By forming a protective layer, the mucus inhibits infection and prevents inflammation.

Adenocarcinomas are, therefore, cancers that begin in these glandular cells, forming small polyps that can continue to grow into malignant tumors.

In the mucosa (or mucosal layer), neuroendocrine tumors (also known as carcinoid tumors) can also develop from cells that secrete hormones and help regulate food intake, gut mobility, and digestion. Neuroendocrine tumors account for less than 1% of colorectal cancer cases.

Like other organs in the gastrointestinal tract, the large intestine is made up of longitudinal muscular tissue that is responsible for moving the digested food matter along through a process known as peristalsis.

While rarely occurring, gastrointestinal stromal tumors (GISTs) can form in these muscle tissues. They often begin as benign growths that can become cancerous, and are thereafter referred to as sarcomas.

Lymphoma is a cancer that begins in the lymph nodes, which are small, bean-shaped organs that help the body fight infections. The lymph nodes located along the colon and rectum are called the regional lymph nodes.

Lymphomas associated with the colon can either originate from the regional lymph nodes, or result from tumors spreading from the colon/rectum.