Key Points about Colon Cancer (Colorectal Cancer)

  • Colorectal cancer affects the colon (lower intestine).
  • The best way to decrease your chances of developing colon cancer is by undergoing regular screening tests after age 40, or sooner if you have certain health risks.
  • Colon cancer is diagnosed using colonoscopy and blood tests.
  • Colon cancer often requires surgery, which may include polypectomy, endoscopic mucosal resection, laparoscopic surgery, partial colectomy, lymph node removal or placement of an ostomy.

Overview

Colon cancer – or colorectal cancer – is cancer that affects the colon, which is also known as the large intestine. Colon cancer typically begins as small, benign (noncancerous) groups of cells called polyps that develop on the inside of the colon. Over time, these polyps can sometimes turn into colon cancer.

Colon cancer causes

Cancer occurs when some cells in the body start to grow abnormally. These abnormal cells grow more quickly than healthy cells, leading to the formation of a lump or mass. Experts don’t know exactly what causes most colon cancers.

Colon cancer risk factors

Factors that can increase your risk for developing colon cancer include:

  • Being a smoker
  • Being African-American
  • Being obese
  • Being over age 50
  • Drinking excessive amounts of alcohol
  • Eating a low-fiber, high-fat diet
  • Having a chronic inflammatory disease of the colon, such as ulcerative colitis (UC) or Crohn’s disease
  • Having a family history of colon cancer
  • Having a personal history of colorectal cancer or polyps
  • Having specific inherited syndromes, including familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer, or HNPCC)
  • Having diabetes
  • Having undergone radiation therapy to the abdomen
  • Not getting enough exercise

Colon cancer symptoms

Signs and symptoms of colon cancer may include:

  • Bleeding from the rectum
  • Bloody stool
  • Change in your bowel habits that persists over time, such as long-lasting diarrhea or constipation
  • Cramps, gas or pain that won’t go away
  • Feeling like your bowel doesn’t completely empty
  • Unintentional weight loss
  • Weakness or fatigue

Colon cancer diagnosis

Your specialist may recommend one or more of the following tests to diagnose colon cancer:

  • Colonoscopy. In this procedure, your specialist uses a long, flexible tube attached to a video camera and specialized viewing monitor to examine your entire colon and rectum. If your specialist sees any abnormal areas, they can use surgical tubes threaded through the tube to take a biopsy (tissue sample) for closer analysis in the lab. You will be under general anesthesia (fully asleep) for this procedure.
  • Blood test. Your specialist may use a blood test to check for clues about your overall health, kidney function and liver function, abnormalities of which may be signs of colorectal cancer.
  • Imaging tests. If your specialist has determined that you have colon cancer, they may order imaging tests – such as abdominal, pelvic or chest computerized tomography (CT) scans – to stage your cancer and determine your course of treatment.

Colon cancer treatment

If you have early-stage colon cancer, your specialist may recommend one or more of the following treatment options:

  • Polypectomy. This treatment involves your specialist completely removing smaller polyps during a colonoscopy procedure.
  • Endoscopic mucosal resection. This treatment involves your specialist removing larger polyps and a small amount of the inner lining of the colon.
  • Laparoscopic surgery. If your polyps can’t be removed during a colonoscopy, your specialist may need to perform minimally invasive surgery to remove the polyps. This involves making several small incisions in your abdomen and using tiny surgical tools attached to cameras to remove the polyps carefully.

If you have late-stage colon cancer, your specialist may recommend one or more of the following treatment options:

  • Partial colectomy. In this procedure, your specialist removes the part of your colon with the cancerous cells, leaving intact as much of the colon and rectum as possible. If appropriate, your specialist will use a minimally invasive approach.
  • Surgery to reroute waste. If your specialist cannot leave enough healthy areas of the colon or rectum in place, you may need surgery to place an ostomy. This involves your surgeon creating an opening in the wall of your abdomen to attach a portion of your remaining bowel. Your stool will exit this hole and drain into a bag that attaches securely over the opening. Depending on your situation, the ostomy may be temporary or permanent.
  • Lymph node removal. In most cases, your surgeon will remove nearby lymph nodes during colon cancer surgery to check them for cancerous cells.
  • Radiation therapy. This treatment uses high-energy beams – such as X-ray or protons – to destroy cancerous cells. People typically have to undergo several rounds of radiation therapy treatment for results.
  • Immunotherapy. This treatment is a medication therapy that helps your immune system fight cancer. 
  • Chemotherapy. This treatment involves using medications – either oral (by mouth) or intravenous (by vein) – to destroy cancer cells.

When should I seek care?

If you experience any of these symptoms, start by voicing your concerns and symptoms to your primary care provider. From there, your doctor may suggest seeing an oncologist for more specialized treatment.