COLON CANCER

 

Colon cancer is a type of cancer that begins in the large intestine (colon). The colon is the final part of the digestive tract.

Colon cancer typically affects older adults, though it can happen at any age. It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. Over time some of these polyps can become colon cancers.

Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.

If colon cancer develops, many treatments are available to help control it, including surgery, radiation therapy and drug treatments, such as chemotherapy, targeted therapy and immunotherapy.

Colon cancer is sometimes called colorectal cancer, which is a term that combines colon cancer and rectal cancer, which begins in the rectum.

Symptoms

Signs and symptoms of colon cancer include:

• A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool
• Rectal bleeding or blood in your stool
• Persistent abdominal discomfort, such as cramps, gas or pain
• A feeling that your bowel doesn't empty completely
• Weakness or fatigue
• Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine.

When to see a doctor

If you notice any persistent symptoms that worry you, make an appointment with your doctor.

Talk with your doctor about when to begin colon cancer screening. Guidelines generally recommend that colon cancer screenings begin around 50. Your doctor may recommend more frequent or earlier screening if you have other risk factors, such as a family history of the disease.

Causes

Doctors aren't certain what causes most colon cancers.

In general, colon cancer begins when healthy cells in the colon develop changes (mutations) in their DNA. A cell's DNA contains a set of instructions that tell a cell what to do.

Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell's DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren't needed. As the cells accumulate, they form a tumor.

With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body to form deposits there (metastasis).

Risk factors

Factors that may increase your risk of colon cancer include:

• Older age. Colon cancer can be diagnosed at any age, but a majority of people with colon cancer are older than 50. The rates of colon cancer in people younger than 50 have been increasing, but doctors aren't sure why.
• African-American race. African-Americans have a greater risk of colon cancer than do people of other races.
• A personal history of colorectal cancer or polyps. If you've already had colon cancer or noncancerous colon polyps, you have a greater risk of colon cancer in the future.
• Inflammatory intestinal conditions. Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk of colon cancer.
• Inherited syndromes that increase colon cancer risk. Some gene mutations passed through generations of your family can increase your risk of colon cancer significantly. Only a small percentage of colon cancers are linked to inherited genes. The most common inherited syndromes that increase colon cancer risk are familial adenomatous polyposis (FAP) and Lynch syndrome, which is also known as hereditary nonpolyposis colorectal cancer (HNPCC).
• Family history of colon cancer. You're more likely to develop colon cancer if you have a blood relative who has had the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.
• Low-fiber, high-fat diet. Colon cancer and rectal cancer may be associated with a typical Western diet, which is low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meat.
• A sedentary lifestyle. People who are inactive are more likely to develop colon cancer. Getting regular physical activity may reduce your risk of colon cancer.
• Diabetes. People with diabetes or insulin resistance have an increased risk of colon cancer.
• Obesity. People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
• Smoking. People who smoke may have an increased risk of colon cancer.
• Alcohol. Heavy use of alcohol increases your risk of colon cancer.
• Radiation therapy for cancer. Radiation therapy directed at the abdomen to treat previous cancers increases the risk of colon cancer.
  

Prevention

Screening colon cancer

Doctors recommend that people with an average risk of colon cancer consider colon cancer screening around age 50. But people with an increased risk, such as those with a family history of colon cancer, should consider screening sooner.

Several screening options exist — each with its own benefits and drawbacks. Talk about your options with your doctor, and together you can decide which tests are appropriate for you.

Lifestyle changes to reduce your risk of colon cancer

You can take steps to reduce your risk of colon cancer by making changes in your everyday life. Take steps to: 

• Eat a variety of fruits, vegetables and whole grains. Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants, which may play a role in cancer prevention. Choose a variety of fruits and vegetables so that you get an array of vitamins and nutrients.
• Drink alcohol in moderation, if at all. If you choose to drink alcohol, limit the amount of alcohol you drink to no more than one drink a day for women and two for men.
• Stop smoking. Talk to your doctor about ways to quit that may work for you.
• Exercise most days of the week. Try to get at least 30 minutes of exercise on most days. If you've been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your doctor before starting any exercise program.
• Maintain a healthy weight. If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. If you need to lose weight, ask your doctor about healthy ways to achieve your goal. Aim to lose weight slowly by increasing the amount of exercise you get and reducing the number of calories you eat.

Colon cancer prevention for people with a high risk

Some medications have been found to reduce the risk of precancerous polyps or colon cancer. For instance, some evidence links a reduced risk of polyps and colon cancer to regular use of aspirin or aspirin-like drugs. But it's not clear what dose and what length of time would be needed to reduce the risk of colon cancer. Taking aspirin daily has some risks, including gastrointestinal bleeding and ulcers.

These options are generally reserved for people with a high risk of colon cancer. There isn't enough evidence to recommend these medications to people who have an average risk of colon cancer.

If you have an increased risk of colon cancer, discuss your risk factors with your doctor to determine whether preventive medications are safe for you.

 

Colon cancer screening: Weighing the options

Colon cancer screening can be an important part of routine health care. If you're not sure which colon cancer screening test is best for you, ask yourself these questions.

If your doctor has recommended colon cancer screening, you might be able to choose from various colon cancer screening tests.

If you're reluctant to make a decision, remember that any discomfort or embarrassment from colon cancer screening is temporary — and detecting problems early could save your life.

Screening tests are used only if you don't have bowel symptoms. If you have signs and symptoms — such as abdominal pain, a change in bowel habits, bleeding, constipation or diarrhea — then you'll need other tests to address these problems.

If you don't have bowel symptoms, consider the following questions to help choose the colon cancer screening test that's best for you.

What preparation is involved?

Preparing for colon cancer screening can be uncomfortable or inconvenient, but it's necessary for the test to be effective. As part of your decision, consider your willingness or ability to follow the preparation instructions for specific colon cancer screening tests.

This may — to varying degrees — include avoiding solid food the day before the exam, adjusting your medications, and using laxatives or enemas to empty your colon.

How convenient is the test?

In addition to test preparation, consider:

• How long the test will take
• How often you need to repeat the test
• Whether you'll need sedation
• How much follow-up care you'll need
• The possible need for follow-up testing to investigate a false-positive finding or to remove tissue

What about cost and insurance issues?

Find out how much each colon cancer screening test costs, as well as which tests your insurance company covers. Consider whether you're willing to pay out of pocket if necessary.

What is your attitude toward screening tests?

The more thorough the colon cancer screening test, the more likely it is to detect any cancer or precancerous polyps. Conversely, a more thorough test might also mean more inconvenient or uncomfortable preparation, a slightly higher risk of serious complications, or both.

Ask yourself:

• Will you feel best if you know you've chosen the most thorough screening test possible?
• Will you worry or doubt the results if you choose a less thorough test?
• How concerned are you about convenience, preparation or the possibility of serious complications?

What is your doctor's approach to screening tests?

Make sure that you're comfortable with the colon cancer screening test your doctor recommends. If your doctor specializes in a particular test, but you'd rather have another test, express your wishes. Your doctor might offer a referral to someone trained in the test with which you feel most comfortable.

What is your risk level?

Your risk of colon cancer might influence your choice of screening tests. If you have an increased risk of colon cancer, your doctor might recommend more frequent colon cancer screening with colonoscopy.

Talk to your doctor about your colon cancer risk if you:

• Have a personal history of colon cancer or precancerous polyps
• Have a parent, sibling or child who has had colon cancer
• Carry a gene for a hereditary colon cancer syndrome
• Have a history of inflammatory bowel disease, such as ulcerative colitis or Crohn's disease

What are the pros and cons of each test?

Multimedia

Here's an overview of the most common colon cancer screening tests.

Colonoscopy

During a colonoscopy exam, a long, flexible tube (colonoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to detect changes or abnormalities inside the entire colon.

Colonoscopy takes about 30 to 60 minutes and screening is generally repeated every 10 years if no abnormalities are found and you don't have an increased risk of colon cancer.

The pros:

• Colonoscopy is one of the most sensitive tests currently available for colon cancer screening.
• The doctor can view your entire colon and rectum.
• Abnormal tissue, such as polyps, and tissue samples (biopsies) can be removed through the scope during the exam.

The cons:

• The exam might not detect all small polyps and cancers.
• A thorough cleansing of the colon is required before the test.
• Diet changes are needed before the test, and medications may need to be adjusted.
• Sedation is almost always used, and it can take several hours to wear off.
• Because of the sedation, you'll need someone to drive you home.
• Rare complications may include bleeding from the site where a biopsy was taken or a polyp or other abnormal tissue was removed, or bleeding from a tear in the colon or rectum wall.
• Cramping or bloating might occur afterward.

Virtual colonoscopy (CT colonography)

During a virtual colonoscopy, a CT scan produces cross-sectional images of the abdominal organs, allowing the doctor to detect changes or abnormalities in the colon and rectum. To help create clear images, a small tube (catheter) is placed inside your rectum to fill your colon with air or carbon dioxide.

Virtual colonoscopy takes about 10 minutes and is generally repeated every five years.

The pros:

• Unlike traditional colonoscopy, virtual colonoscopy doesn't require sedation or the insertion of a scope into the colon.

The cons:

• Like standard colonoscopy, a thorough cleansing of the bowel is required beforehand.
• The exam might not detect all small polyps and cancers.
• Diet changes are needed before the test, and medications may need to be adjusted.
• Radiation exposure may be a concern. However, the level of radiation used during a screening CT scan is lower than the amount used in a diagnostic CT scan.
• Since tissue samples can't be taken during the exam, a follow-up colonoscopy might be needed if an abnormality is detected.
• Cramping or bloating might occur afterward.

Fecal occult blood test or fecal immunochemical test

Fecal occult blood test (FOBT) and fecal immunochemical test (FIT) are lab tests used to check stool samples for hidden (occult) blood. The tests usually are repeated annually.

The pros:

• Stool sample collection can be done at home.
• There's no need to empty the colon ahead of time.
• There's no need for sedation.

The cons:

• The tests fail to detect some polyps and cancers.
• Certain foods and medications might need to be avoided for several days before the test.
• If blood is detected, additional tests might be needed to determine the source.
• The tests can suggest an abnormality when none is present (false-positive result).

Flexible sigmoidoscopy

During flexible sigmoidoscopy, a thin, flexible tube is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the rectum and most of the lower part of the colon (sigmoid colon).

A flexible sigmoidoscopy test takes about 20 minutes and is generally repeated every 5 years.

The pros:

• Sedation isn't usually needed.
• Bowel cleansing is less extensive than preparation for colonoscopy.
• Biopsies can be taken through the scope during the exam.

The cons:

• Any abnormalities in the upper colon won't be found.
• Some bowel cleansing is needed before the test.
• You might need to change your diet or medications before the test.
• Rare complications may include bleeding or a tear in the lining of the colon.
• Cramping or bloating might occur after the exam.
• Additional tests might be necessary if an abnormality is detected.

Stool DNA test

The stool DNA test uses a sample of your stool to look for DNA changes in cells that might indicate the presence of colon cancer or precancerous conditions. The stool DNA test also looks for signs of blood in your stool.

For this test, you collect a stool sample at home and send it to a laboratory for testing. Stool DNA testing is typically repeated every three years.

The pros:

• The test doesn't require bowel preparation, sedation or insertion of a scope.
• You can eat and drink normally, and take your normal medications, before the test.
• The stool can be collected at home, avoiding disruption of work and daily activities.

The cons:

• The DNA stool test is less sensitive than colonoscopy at detecting precancerous polyps.
• If abnormalities are found, additional tests might be needed.

What's the bottom line?

Choosing a colon cancer screening test may not be an easy decision, but it's a potentially lifesaving one. Consult your doctor about your colon cancer screening options.

Commit to a screening schedule based on your personal risk factors. Remember, the earlier colon cancer is detected, the easier it is to treat.