Colorectal Cancer

Colorectal cancer starts in the colon or the rectum, usually as a growth on the inner lining of the organ. These growths are called polyps and affects both men and women. Some polyps can become cancerous, but not all.  Luckily, they can be identified during routine colonoscopies. To learn about cancer screenings for colorectal cancers- visit our Cancer Screening Education Page.

What Makes Up the Colon

The colon and rectum make up the large intestine. The majority of this 5 ft long organ is the colon, which is a muscular tube. The colon is named by parts in which food travel through. The first section is called the ascending colon. It starts with a pouch called the cecum, where undigested food is comes in from the small intestine. It extends upward on the right side of the abdomen. The second section is called the transverse colon. It goes across the abdomen from the right to the left side. The third section is called the descending colon because it travels downward on the left side of the body. The fourth section is called the sigmoid colon because it has an “S” shape. The sigmoid colon joins the rectum, which connects to the anus. The ascending and transverse sections together are called the proximal colon. The descending and sigmoid colon are called the distal colon.

What Does the Colon Do

The colon absorbs water and salt from the remaining food matter after it goes through the small intestine. The waste matter that’s left after going through the colon goes into the rectum, the final 6 inches of the digestive system. It’s stored there until it passes out of the body through the anus. Ring-shaped sphincter muscles around the anus keeps stool from coming out until they relax during a bowel movement.

Types of Colon and Rectal Cancers

  • Adenocarcinomas make up about 96% of colorectal cancers. These cancers start in cells that make mucus to lubricate the inside of the colon and rectum.
  • Carcinoid tumors start from special hormone-making cells in the intestine.
  • Gastrointestinal stromal tumors (GISTs) start from special cells in the wall of the colon called the interstitial cells of Cajal. These tumors can be found anywhere in the digestive tract, but are not common in the colon. Not all stromal tumors are cancerous.
  • Lymphomas are cancers of immune system cells and they usually start in lymph nodes, but they can also start in the colon, rectum, or other organs.
  • Sarcomas can start in blood vessels, muscle layers, or other connective tissues in the wall of the colon and rectum, but this is rare.

Risk Factors for Colorectal Cancers

There are some risk factors that you may be able to change yourself, such as maintaining a healthy weight, exercising. People with Type 2 Diabetes have an increased risk of colorectal cancer. Limit your intake of red meats, and avoid cooking meats at very high temperatures such as frying, broiling, or grilling, as these forms of cooking create chemicals that might raise your cancer risk. These risks have an unknown impact for colorectal cancers, but are being further studied. Smoking and heavy alcohol intake are also risk factors.

Ethnical risks- African Americans have the highest colorectal cancer incidence and mortality rates of all racial groups in the United States.  Jews of Eastern European descent (Ashkenazi Jews) have one of the highest colorectal cancer risks of any ethnic group in the world.

Some risk factors that cannot be changed are your age, and medical history including the following:

  • If you have a history of adenomatous polyps (adenomas), you are at increased risk of developing colorectal cancer.
  •  If you’ve had colorectal cancer, even though it was completely removed, you are more likely to develop new cancers in other parts of the colon and rectum.
  • If you have inflammatory bowel disease (IBD), including either ulcerative colitis or Crohn’s disease, your risk of colorectal cancer is increased.
  • Most colorectal cancers are found in people without a family history of colorectal cancer. Though nearly 1 in 3 people who develop colorectal cancer have other family members who have had it. People with a family history of colorectal cancer in a first-degree relative (parent, sibling, or child) are at increased risk. The risk is even higher if that relative was diagnosed with cancer when they were younger than 45, or if more than one first-degree relative was diagnosed.

Colon Cancer Screening Protocols

The recommended age for both men and women who have normal risk for developing colon cancer should start colonoscopies at age 45 and repeat at regular intervals, suggested to be every 7-10 years until or after age 75.

For those at higher risk, screenings are recommended before age 45 such as this who have:

  • a family history of colon cancer or certain types of polyps
  • personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
  • family history of hereditary colorectal cancer syndrome such as familial adenomatous polyposis (FAP) or Lynch syndrome (also known as hereditary non-polyposis colon cancer or HNPCC
  • prior radiation treatments to the abdomen or pelvic area to treat cancer


  • Surgery
  • Radiation Therapy
  • Chemotherapy
  • Targeted Drug Therapies
  • Immunotherapy