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Colorectal Cancer: Overview

What is colorectal cancer?

Cancer is made of changed cells that grow out of control. The changed (abnormal) cells often grow to form a lump or mass called a tumor. Cancer cells can also grow into (invade) nearby areas. And they can spread to other parts of the body. This is called metastasis.

Colorectal cancer is cancer that starts in either your colon or your rectum. These make up the lower part of your digestive tract. In most cases cancer does not start in both the colon and rectum. But both types of cancer have a lot in common. So they are often called colorectal cancer.

The colon and rectum make up the large intestine. This is sometimes called the large bowel. The colon is a muscular tube about 5 feet long that forms the last part of the digestive tract. It absorbs water from the remaining food matter. The rectum is the last 6 inches of the digestive tract. It acts as a storage space before waste (feces or stool) leaves the body through the anus. The colon and rectum have an inner lining made of millions of cells.

Changes that occur in the cells that line the inside of the colon or rectum can lead to growths called polyps. Over time, some types of polyps can become cancer. A type of polyp that can develop into cancer is called an adenomatous polyp.  Adenocarcinoma is the most common type of colorectal tumor. Removing polyps early may stop cancer from ever forming.

Who is at risk for colorectal cancer?

A risk factor is anything that may increase your chance of having a disease. The exact cause of someone’s cancer may not be known. But risk factors can make it more likely for a person to have cancer. Some risk factors may not be in your control. But others may be things you can change.

The risk factors for colorectal cancer include:

  • Being over age 50

  • Being African American or Ashkenazi Jewish

  • Being male

  • History of colorectal polyps

  • History of colorectal cancer

  • Ulcerative colitis or Crohn's disease

  • Family history of the disease

  • Certain inherited syndromes, such as Lynch syndrome (HNPCC) or familial adenomatous polyposis (FAP)

  • Obesity

  • Not being active

  • A diet high in red meats and processed meats

  • Drinking a lot of alcohol

  • Type 2 diabetes

  • Smoking

Talk with your healthcare provider about your risk factors for colorectal cancer and what you can do about them.

Can colorectal cancer be prevented?

There's no sure way to prevent colorectal cancer. But you can make changes that will help you control some of the risks.  Having a healthy lifestyle may help to lower your risk for colorectal cancer. This includes:

  • Being physically active

  • Eating lots of fruits, vegetables, and whole grains

  • Limiting red and processed meats

  • Staying at a healthy weight

  • Not smoking or abusing alcohol

  • Getting enough calcium in your diet

  • Consider taking aspirin if you also have heart disease or chronic pain

  • Talking with your provider about screening for colorectal polyps and cancer

  • Discussing menopausal hormone use with your provider

Talk with your healthcare provider about what you can do to help prevent colorectal cancer.

Are there screening tests for colorectal cancer? 

Colorectal cancer may be found with a screening test. Screening means checking for a health problem before a person has symptoms. It may find some types of cancer early, when they’re often easier to treat. The screening tests to find polyps and/or colorectal cancer are:

  • Flexible sigmoidoscopy

  • Colonoscopy

  • Virtual colonoscopy (CT colonography)

  • Fecal occult blood test (FOBT) or fecal immunochemical test (FIT)

  • Stool DNA test

Talk with your healthcare provider to make an informed decision about screening.

What are the symptoms of colorectal cancer?

People with colorectal cancer often do not have symptoms right away. By the time symptoms occur, the cancer may have grown or spread to other organs. This can make it harder to treat. That’s why routine colorectal cancer screening is important. Symptoms can include:

  • A change in bowel habits that lasts for more than a few days, such as diarrhea, constipation, or a feeling that your bowel is not empty after a bowel movement

  • Bright red or very dark blood in your stool

  • Constant tiredness

  • Stools that are thinner than usual

  • Stools that look slimy or have mucous on them

  • Ongoing gas pains, bloating, fullness, or cramps

  • Unexplained weight loss

  • Vomiting

Many of these may be caused by other health problems. But it is important to see your healthcare provider if you have these symptoms. Only a healthcare provider can tell if you have cancer.

How is colorectal cancer diagnosed?

If your healthcare provider thinks you may have colorectal cancer, you will need exams and tests to be sure. Your healthcare provider will ask you about your health history, your symptoms, risk factors, and family history of disease. He or she will also give you a physical exam. For colorectal cancer, a biopsy is the only way to be sure of the diagnosis. The most common type of biopsy is an endoscopic biopsy. This is usually done during a colonoscopy. Once your healthcare provider removes the tissue, it is checked for cancer cells. It usually takes several days for the results of your biopsy to come back. 

After a diagnosis of colorectal cancer, you may have other tests. These help your healthcare providers learn more about the cancer. They can help determine the stage of the cancer. The stage is how much and how far the cancer has spread (metastasized) in your body. It is one of the most important things to know when deciding how to treat the cancer.

Once your cancer is staged, your healthcare provider will talk with you about what the stage means for your treatment. Be sure to ask your healthcare provider to explain the stage of your cancer to you in a way you can understand.

How is colorectal cancer treated?

Your treatment choices depend on the type of colorectal cancer you have, test results, and the stage of the cancer. The goal of treatment is may be to cure you, control the cancer, or help ease problems caused by the cancer. Talk with your healthcare team about your treatment choices, the goals of treatment, and what the risks and side effects may be.

Types of treatment for cancer are either local or systemic. Local treatments remove, destroy, or control cancer cells in one area. Surgery and radiation are local treatments. Systemic treatment is used to destroy or control cancer cells that may have traveled around your body. When taken by pill or injection, chemotherapy is a systemic treatment. You may have just one treatment or a combination of treatments.

Types of treatment for colorectal cancer include:

  • Surgery

  • Chemotherapy

  • Radiation therapy

  • Targeted therapy

  • Immunotherapy

  • Ablation and embolization

  • Supportive care to ease your symptoms

Researchers are always looking for new ways to treat cancer. These new methods are tested in clinical trials. Talk with your doctor to find out if there are any clinical trials you should consider.

Talk with your healthcare providers about your treatment options. Make a list of questions. Think about the benefits and possible side effects of each option. Talk about your concerns with your healthcare provider before making a decision.

What are treatment side effects?

Cancer treatment such as chemotherapy and radiation can damage normal cells. This can cause side effects such as hair loss, mouth sores, and vomiting. Talk with your healthcare provider about side effects you might have and ways to manage them.  There may be things you can do and medicines you can take to help prevent or control side effects.

Colorectal cancer and its treatment may permanently change the way you pass stool from your body. You may have a colostomy. This is a new opening (stoma) and a pouch that collects stool.

Coping with colorectal cancer

Many people feel worried, depressed, and stressed when dealing with cancer. Getting treatment for cancer can be hard on your mind and body. Keep talking with your healthcare team about any problems or concerns you have. Work together to ease the effect of cancer and its symptoms on your daily life.

Here are tips:

  • Talk with your family or friends.

  • Ask your healthcare team or social worker for help.

  • Speak with a counselor.

  • Talk with a spiritual advisor, such as a minister or rabbi.

  • Ask your healthcare team about medicines for depression or anxiety.

  • Keep socially active.

  • Join a cancer support group.

Cancer treatment is also hard on the body. To help yourself stay healthier, try to:

  • Eat a healthy diet, with as many protein foods as possible.

  • Drink plenty of water, fruit juices, and other liquids.

  • Keep physically active.

  • Rest as much as needed.

  • Talk with your healthcare team about ways to manage treatment side effects.

  • Take your medicines as directed by your team.

When should I call my healthcare provider?

Your healthcare provider will talk with you about when to call. You may be told to call if you have any of the below:

  • New symptoms or symptoms that get worse

  • Signs of an infection, such as a fever

  • Side effects of treatment that affect your daily function or don't get better with treatment

Ask your healthcare provider what signs to watch for, and when to call. Know how to get help after office hours and on weekends and holidays. 

Key points about colorectal cancer

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your provider tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your provider if you have questions.

Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 2/1/2019
© 2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.