Colon

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.

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.

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.

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.

Diagnosis:

If your signs and symptoms indicate that you could have colon cancer, your doctor may recommend one or more tests and procedures, including:

Colonoscopy:

Using a scope to examine the inside of your colon (colonoscopy). Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view your entire colon and rectum. If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis and remove polyps.

Blood tests:

No blood test can tell you if you have colon cancer. But your doctor may test your blood for clues about your overall health, such as kidney and liver function tests.

Your doctor may also test your blood for a chemical sometimes produced by colon cancers (carcinoembryonic antigen, or CEA). Tracked over time, the level of CEA in your blood may help your doctor understand your prognosis and whether your cancer is responding to treatment.

Determining the extent of the cancer

If you’ve been diagnosed with colon cancer, your doctor may recommend tests to determine the extent (stage) of your cancer. Staging helps determine what treatments are most appropriate for you.

Staging tests may include imaging procedures such as abdominal, pelvic and chest CT scans. In many cases, the stage of your cancer may not be fully determined until after colon cancer surgery.

The stages of colon cancer are indicated by Roman numerals that range from 0 to IV, with the lowest stages indicating cancer that is limited to the lining of the inside of the colon. By stage IV, the cancer is considered advanced and has spread (metastasized) to other areas of the body.

Treatment

In cancer care, different types of doctors often work together to create a patient’s overall treatment plan that usually includes or combines different types of treatments. This is called a multidisciplinary team.

Treatment options and recommendations depend on several factors, including the type and stage of cancer, possible side effects, and the patient’s preferences and overall health.

Surgery is the removal of the tumor and some surrounding healthy tissue during an operation. It is often called surgical resection. This is the most common treatment for colorectal cancer. Part of the healthy colon or rectum and nearby lymph nodes will also be removed.

Laparoscopic surgery:

Some patients may be able to have laparoscopic colorectal cancer surgery. With this technique, several viewing scopes are passed into the abdomen while a patient is under anesthesia. Anesthesia is medicine that blocks the awareness of pain. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. Laparoscopic surgery is as effective as conventional colon surgery in removing the cancer. Surgeons who perform laparoscopic surgery have been specially trained in that technique.

Colostomy for rectal cancer:

Less often, a person with rectal cancer may need to have a colostomy. This is a surgical opening, or stoma, through which the colon is connected to the abdominal surface to provide a pathway for waste to exit the body. This waste is collected in a pouch worn by the patient. Sometimes, the colostomy is only temporary to allow the rectum to heal, but it may be permanent. With modern surgical techniques and the use of radiation therapy and chemotherapy before surgery when needed, most people who receive treatment for rectal cancer do not need a permanent colostomy.