This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on April 29, 2022.

About colorectal cancer

Colorectal cancer (of the colon and/or rectum) is the fourth-most common cancer in the United States, according to the National Cancer Institute Surveillance, Epidemiology, and End Results Program (SEER).

Together, the colon and rectum make up the large intestine. The colon, which is about 5 feet long, helps digest food and remove nutrients and water before sending the waste to the rectum, the final few inches of the intestine.

The section attached to the small intestine goes along the right side of the belly and is called the ascending colon. It crosses from right to left (transverse colon) and then goes down the left side (descending colon), until it finally curves in an S-like shape (sigmoid colon) to connect with the inches-long rectum. The first two sections of the colon are called the proximal colon, while the latter half is called the distal colon. Being familiar with these terms may help patients understand exactly where the cancer is located. Colorectal cancer may develop when:

  • Polyps, mushroom-like growths inside the colon, grow and become cancerous.
  • Cells along the lining of the colon or rectum mutate and grow out of control, forming a tumor.

Colorectal cancer types

More than 95 percent of all colorectal cancers are adenocarcinomas of the colon or rectum. Colorectal adenocarcinomas form in glands that secrete fluids to lubricate the colon and rectum. Adenocarcinomas are found in most common cancers, including breast cancer, prostate cancer and pancreatic cancer.

Other types of colorectal cancer include:

Recurrent colorectal cancer is cancer that returns to the same part of the colon or rectum where it was originally diagnosed.

Colorectal cancer that has spread to other parts of the body is referred to as metastatic. When it spreads, colorectal cancer is most often found in the liver, but it may also travel to the lungs, bone and/or brain.

Learn more about colorectal cancer types

Symptoms of colorectal cancer

Symptoms may include:

  • Incomplete bowel movements (the feeling of being unable to empty bowels completely)
  • Rectal bleeding or blood in the stool
  • Thin, ribbon-like stools
  • Diarrhea and/or constipation
  • Stomach pains, bloating, fullness or cramps that occur frequently and don’t go away
  • Unexplained weight loss and/or loss of appetite
  • Fatigue
  • Nausea or vomiting
  • Bowel habit changes

While colorectal cancer may cause these symptoms, other conditions may cause them, too. Patients who notice any of these symptoms should visit their doctor.

Learn more about colorectal cancer symptoms

Who gets colorectal cancer?

The American Cancer Society estimates that 149,500 people will be diagnosed with colorectal cancer in 2021.

Some risk factors may increase a person’s chances of developing this disease, including:

  • Age (after 50)
  • Race and ethnicity (African-American, American Indian, Alaska Native or Ashkenazi Jewish heritage)
  • Family history of colorectal cancer or polyps
  • History of polyps, especially if they were large, numerous, or showed certain abnormal noncancerous cells (dysplasia)
  • Previous colorectal cancer diagnosis
  • Inflammatory bowel disease (IBD), including ulcerative colitis (UC) or Crohn's disease 
  • Certain genetic syndromes, such as Lynch syndrome or familial adenomatous polyposis (FAP)
  • Type 2 diabetes

Lifestyle factors that may increase the risk of colorectal cancer risk include:

  • Diet high in fat, red meats and/or processed meats 
  • Unhealthy weight or obesity, especially for men
  • Sedentary lifestyle
  • Moderate to heavy alcohol consumption
  • Tobacco use

Learn more about risk factors for colorectal cancer

Diagnosing colorectal cancer

Colorectal cancer may be detected and treated early with a proper screening regimen.

A number of tests are available to diagnose colorectal cancer. In fact, a combination of these tests may be needed to make a diagnosis:

Learn more about colorectal cancer diagnosis and detection

Treatment for colorectal cancer

Colorectal cancer treatments may be localized, focusing on a tumor, or systemic, using drugs to fight cancer cells throughout the body. A treatment plan is determined by the cancer’s stage and extent of the disease.

These options may include:

Learn more about treatments for colorectal cancer

Survival rates for colorectal cancer

The earlier colorectal cancer is found, the better the chances of survival. About 65 percent of patients are still alive five years after a diagnosis, according to the SEER Program. If colorectal cancer is detected before it’s spread to other parts of the body, the five-year survival rate increases to 90 percent.

Ongoing research is focused on uncovering the causes of colorectal cancer, improving screening tests, defining subtypes of colorectal cancer, and testing new drugs to fight it.

Learn more about colon cancer survival rates and rectal cancer survival rates