Colorectal (Colon) Cancer

What is colorectal cancer?

The large intestine is the last part of the digestive tract. It has two components: the colon, which makes up the first six feet of the large intestine, and the rectum, which makes up the last six inches and ends in the anus. Cancers of the colon and rectum are often grouped together as colorectal cancer.

Colorectal cancers occur when the cells of the colon or rectum divide uncontrollably. The majority of colorectal cancers start as polyps, which are small overgrowths of tissue in the lining of the colon. Most polyps are benign (non-cancerous), but some may grow out of control and become cancerous.

More specifically, most cases of colorectal cancer are adenocarcinomas. Adenocarcinoma refers to cancers that begin in the mucus-producing gland cells that line the intestine. These gland cells can be found within polyps. While there are a few other types of colon cancers, they are rare and treated differently.

Most precancerous polyps produce few if any symptoms, so it is important to get screened regularly for colon cancer. Colorectal cancer screenings allow your doctor to find ad remove polyps before they turn into cancer. 

To learn more about colon cancer screenings, visit our Colorectal Cancer Screening Exams page.

Types of colorectal cancer

The majority of colorectal cancers are adenocarcinomas that began as adenomas, which are a type of polyp that may become cancer.

Symptoms

Colorectal cancer usually starts off in small polyps (overgrowth of tissue) in the colon or rectum. These polyps may not produce any symptoms, especially in the early stages. As the disease progresses, more symptoms may appear. 

Symptoms of colorectal cancer may include:

• Diarrhea or constipation that does not go away
• Change in normal bowel habits, such as size, shape, and frequency
• Discomfort or urge to have a bowel movement when there is no need
• Abdominal pain or cramping pain in your lower stomach
• Bloating or full feeling
• Change in appetite
• Rectal bleeding
• Blood in the stool or toilet after a bowel movement
• Excessive fatigue
• Weight loss without dieting

In the later stages of colon cancer, the polyp may metastasize (spread) to other parts of the body. This can cause other symptoms, depending on where cancer has spread.

These symptoms usually do not mean you have colorectal cancer. But, any time you notice unexplained changes and they persist for more than two weeks, don’t assume they will just go away. See your doctor.

Risk factors

Anything that increases your chance of getting colorectal cancer is a risk factor.  Colorectal cancer risk factors include:

• Age: Colorectal cancer is most frequently diagnosed in people aged 65-74. 
  • The median age at diagnosis is 67 years old
• Race: African Americans have the highest rate of colon cancer among all racial groups in the United States.
  
• Family history of colon cancer, rectal cancer, or polyps
• Inflammatory bowel disease (Crohn’s disease or chronic ulcerative colitis)
  
• Prior history of colorectal cancer or polyps
• Hereditary cancer syndromes: Some genetic mutations can be inherited and increase your risk for certain types of cancer. Inherited syndromes including hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome and familial adenomatous polyposis (FAP) may put you at higher risk for developing colon cancer.

For patients concerned about inherited family syndromes that cause colorectal cancer, we offer advanced genetic testing and counseling to help understand your risk.

Lifestyle factors that increase your colorectal cancer risk include:

• Obesity
• Lack of exercise
• Diet: If you eat a lot of red meat, processed meats, or meats cooked at very high heat, you may be at higher risk for colon cancer
• Sedentary lifestyle
• Cigarette smoking
• Drinking too much alcohol

Prevention

Lifestyle choices that may decrease your risk of getting colon cancer include:

• Regular screening tests
• Staying at a healthy weight
• Regular exercise
• Eating a healthy diet with lots of fruits and vegetables
• Avoiding cigarette smoking
• Drinking alcohol only in moderation

Learn about ways to manage your colorectal cancer risk 

Related: Colorectal cancer prevention: What you need to know

Learn more about colorectal cancer:

• Colorectal cancer symptoms
• Colorectal cancer diagnosis
• Colorectal cancer treatment

Why choose MD Anderson for your colorectal cancer treatment?

At MD Anderson's Colorectal Center, your colorectal cancer treatment is personalized to provide the best outcomes, while focusing on your quality of life. We offer leading-edge treatments for colorectal cancer, including advanced minimally invasive surgeries that provide successful treatment with less impact on you.

MD Anderson is also uniquely experienced in sphincter-preserving surgeries, eliminating the need for a colostomy. 

Multidisciplinary Team Approach

Colorectal cancer treatment at MD Anderson is provided by a team of experts, including medical oncologists, surgeons, radiation oncologists, gastroenterologists, radiologists, clinical nurses, and mid-level providers, working in concert, to optimize your care. They discuss your case and develop a treatment designed to attack your cancer while minimizing side effects. 

Supplementing your clinical care, MD Anderson teams also provide assistance with nutrition, pain management, psychological support, wound management and other ancillary needs, in a holistic approach that treats not only your cancer, but you as an individual. 

In addition, our advanced knowledge in cancer genetics can help diagnose and treat inherited family syndromes that may increase your risk of colorectal cancer. This expertise also helps us work with you to plan the most effective treatment for your specific condition.

Leading-Edge Advancements

As one of the world’s largest cancer research centers, MD Anderson is a leading center for the investigation into new methods of colorectal cancer treatment and diagnosis. Through our clinical trials, this research can give patients access to treatments and procedures not found anywhere else.