Colorectal cancer - symptoms and causes (2023)


colon cancer

Colorectal cancer - symptoms and causes (1)

colon cancer

Colon cancer can occur in any part of the colon. Examination of the entire colon with a long, flexible tube equipped with a camera (colonoscopy) is one way to screen for colon cancer and polyps.

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

Colon cancer usually affects older adults, although it can occur at any age. It usually starts with small noncancerous (benign) clumps of cells called polyps that form inside the colon. Over time, some of these polyps can develop into colon cancer.

Polyps can be small and cause few or no symptoms. For this reason, doctors recommend regular checkups to help prevent colon cancer by detecting and removing polyps before they turn into cancer.

(Video) 6 Warning Signs of Colon Cancer

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

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


Colon cancer signs and symptoms include:

  • A persistent change in bowel habits, including diarrhea or constipation, or a change in stool consistency
  • Rectal bleeding or blood in the stool
  • Persistent abdominal discomfort, such as cramping, bloating, or pain
  • A feeling that your bowels are not emptying completely
  • weakness or tiredness
  • unexplained weight loss

Many people with colon cancer have no symptoms in the early stages of the disease. When symptoms do appear, they are likely to vary depending on the size and location of the colon cancer.

when to the doctor

If you notice persistent symptoms that worry you, make an appointment to see your doctor.

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(Video) Mayo Clinic Minute: Symptoms of colon cancer

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Doctors are not sure what causes most colon cancers.

In general, colon cancer begins when healthy colon cells 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 it becomes cancerous, the cells continue to divide – even when no new cells are needed. When cells accumulate, they form a tumor.

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

risk factors

Factors that may increase your risk of colon cancer include:

  • Elderly.Colon cancer can be diagnosed at any age, but most people with colon cancer are over age 50. Colon cancer rates are rising in people under age 50, but doctors aren't sure why.
  • African American race.African Americans have a higher risk of colon cancer than people of other races.
  • A personal history of colon cancer or polyps.If you've had colon cancer or benign colon polyps, you have a higher risk of developing colon cancer in the future.
  • Inflammatory bowel diseases.Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase the risk of colon cancer.
  • Hereditary syndromes that increase the risk of colon cancer.Some genetic mutations, passed down through generations in your family, can significantly increase your risk of colon cancer. Only a small percentage of colon cancers are linked to inherited genes. The most common inherited syndromes that increase the risk of colon cancer are familial adenomatous polyposis (FAP) and Lynch syndrome, also known as hereditary non-polyposis colon cancer (HNPCC).
  • Family history of colon cancer.You are 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, the risk is even greater.
  • Diet low in fiber and high in fat.Colon cancer and rectal cancer can be linked to a typical Western diet that 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 a diet high in red meat and processed meat.
  • A sedentary lifestyle.Inactive people are more likely to develop colon cancer. Regular physical activity can reduce the risk of colon cancer.
  • Diabetes.People with diabetes or insulin resistance have an increased risk of colon cancer.
  • Obesity.People who are overweight have an increased risk of developing colon cancer and an increased risk of dying from colon cancer compared with people considered to be of normal weight.
  • Smoke.People who smoke may have an increased risk of colon cancer.
  • Alcohol.Heavy alcohol consumption increases the risk of colon cancer.
  • Radiotherapy for cancer.Radiation therapy directed to the abdomen to treat earlier cancers increases the risk of colon cancer.


Colon cancer screening

Doctors recommend that people with an average risk of colon cancer consider screening for colon cancer around age 45. But people at higher risk, such as

There are several screening options - each with its own advantages and disadvantages. Talk to your doctor about your options, and together you can decide which tests are right for you.

Lifestyle changes to reduce colon cancer risk

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

  • Eat a variety of fruits, vegetables and whole grains.Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants that may play a role in cancer prevention. Choose a variety of fruits and vegetables to get a variety of vitamins and nutrients.
  • Drink alcohol in moderation, if at all.If you decide 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 smokingTalk to your doctor about ways to quit that might work for you.
  • Exercise most days of the week.Try to get at least 30 minutes of exercise most days. If you've been inactive, start slowly and gradually build up to 30 minutes. Also, talk to your doctor before starting any exercise program.
  • Maintain a healthy weight.If you're at a healthy weight, work to maintain it by combining a healthy diet with daily exercise. If you need to lose weight, consult your doctor about healthy ways to reach your goal. Try to lose weight slowly by increasing the amount of exercise and reducing the number of calories you eat.

Colorectal cancer screening for high-risk people

Some drugs have been found to reduce the risk of precancerous polyps or colon cancer. For example, some evidence links a reduced risk of polyps and colon cancer with regular use of aspirin or aspirin-like medications. However, it is not clear what dose and how long it would take to reduce the risk of colon cancer. Taking aspirin every day carries some risks, including gastrointestinal bleeding and ulcers.

(Video) What causes colorectal cancer?

These options are generally reserved for people who are at high risk for colon cancer. There is not enough evidence to recommend these drugs for people with an average risk of colon cancer.

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

More information

  • Colorectal Cancer Care at the Mayo Clinic
  • Colorectal Cancer Prevention
  • Colon Cancer Screening: At What Age Can You Stop?

By the staff at the Mayo Clinic



1. What Are the Symptoms of Colorectal Cancer?
(Roswell Park Comprehensive Cancer Center)
2. Colorectal carcinoma - causes, symptoms, diagnosis, treatment, pathology
(Osmosis from Elsevier)
3. Warning Signs of Colon Cancer
(Cleveland Clinic)
4. Risks and symptoms of colorectal cancer - Mayo Clinic
(Mayo Clinic)
5. Tori’s Story: Colon Cancer Warning Signs
(Henrico Doctors' Hospitals)
6. Colon Cancer Symptoms | Colorectal Cancer | 10 warning signs of Colon Cancer | Colon Cancer
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