Colon Cancer

Colon cancer is a disease in which malignant (cancer) cells form in the tissues of the colon. Also called colorectal cancer, it is a major problem in the Western world, ranking as the second most common cause of cancer-related death. Individuals have a 5% lifetime risk of getting colorectal cancer in the United States.^[1] Although it has many contributing causes, one of the strongest associated risk factors for colorectal cancer is a family history of the disease.

The colon is part of the body's digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Gastrointestinal (digestive) system anatomy; shows esophagus, liver, stomach, colon, small intestine, rectum, and anus; Source:NCI

Symptoms

Possible signs of colon cancer include a change in bowel habits or blood in the stool.

These and other symptoms may be caused by colon cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• A change in bowel habits.
• Blood(either bright red or very dark) in the stool.
• Diarrhea, constipation, or feeling that the bowel does not empty completely.
• Stools that are narrower than usual.
• Frequent gas pains, bloating, fullness, or cramps.
• Weight loss for no known reason.
• Feeling very tired.
• Vomiting.

Diagnosis

Tests that examine the rectum, rectal tissue, and blood are used to detect (find) and diagnose colon cancer.

The following tests and procedures may be used:

• Physical exam and history: A history of the patient's health habits and past illnesses and treatments will also be taken. An exam of the body to check general signs of health, including checking for signs of disease, such as lumps.
• Fecal occult blood test: A test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.

Fecal Occult Blood Test (FOBT) kit; shows card, applicator, and return envelope, Source:NCI

• Digital rectal exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the rectum to feel for lumps or anything else that seems unusual.
• Barium enema: A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. A series of x-rays are then taken of the lower gastrointestinal tract. This procedure is also called a lower GI series.

Barium enema procedure; shows barium liquid being put into the rectum and flowing through the colon. Inset shows person on table having a barium enema; Source:NCI

• Sigmoidoscopy: A procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope is inserted through the rectum into the sigmoid colon. A sigmoidoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.

Sigmoidoscopy; shows sigmoidoscope inserted through the anus and rectum and into the sigmoid colon. Inset shows patient on table having a sigmoidoscopy.Source:NCI

• Colonoscopy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope is inserted through the rectum into the colon. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.

Colonoscopy; shows colonoscope inserted through the anus and rectum and into the colon. Inset shows patient on table having a colonoscopy. Source:NCI

• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
• Virtual colonoscopy: A procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography.

Staging Colon Cancer

After colon cancer has been diagnosed, tests are done to find out if cancer cells have spread within the colon or to other parts of the body.

The process used to find out if cancer has spread within the colon or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

• CT Scan(CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.
• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells,white blood cells, and platelets.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.
• Carcinoembryonic antigen (CEA) assay: A test that measures the level of CEA in the blood. CEA is released into the bloodstream from both cancer cells and normal cells. When found in higher than normal amounts, it can be a sign of colon cancer or other conditions.
• MRI(magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the colon. A substance called gadolinium is injected into the patient through a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• Surgery: A procedure to remove the tumor. Portions of the colon surrounding the tumor, as well as neihboring lymph nodes, are also excised. This helps determine how far the cancer has spread through the colon.

The following stages are used for colon cancer

Colon cancer staging; shows tumors growing through layers of the colon wall for Stage 0, Stage I, Stage II, Stage III, and Stage IV colon cancer. Inset shows serosa, muscle, submucosa and mucosa layers of the colon wall, and lymph nodes and blood vessels. Source:NCI

As colon cancer progresses from Stage 0 to Stage IV, the cancer cells grow through the layers of the colon wall, spreading to lymph nodes and other organs.

• In Stage 0, abnormal cells are found in the innermost lining of the colon. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

• In Stage I , cancer has formed and spread beyond the innermost tissue layer of the colon wall to the middle layers. Stage I colon cancer is sometimes called Dukes A colon cancer.

• Stage II colon cancer is divided into stage IIA and stage IIB.

• Stage IIA: Cancer has spread beyond the middle tissue layers of the colon wall or has spread to nearby tissues around the colon or rectum.
• Stage IIB: Cancer has spread beyond the colon wall into nearby organs and/or through the peritoneum (the memberane that covers the outside of the colon).

Stage II colon cancer is sometimes called Dukes B colon cancer.

• Stage III colon cancer is divided into stage IIIA, stage IIIB, and stage IIIC.

• Stage IIIA: Cancer has spread from the innermost tissue layer of the colon wall to the middle layers and has spread to as many as 3 lymph nodes.
• Stage IIIB: Cancer has spread to as many as 3 nearby lymph nodes and has spread:
  • Beyond the middle tissue layers of the colon wall; or
  • To nearby tissues around the colon or rectum; or
  • Beyond the colon wall into nearby organs and/or through the peritoneum.
• Stage IIIC: Cancer has spread to 4 or more nearby lymph nodes and has spread:
  • To or beyond the middle tissue layers of the colon wall; or
  • To nearby tissues around the colon or rectum; or
  • To nearby organs and/or through the peritoneum.

Stage III colon cancer is sometimes called Dukes C colon cancer.

• Stage IV colon cancer is sometimes called Dukes D colon cancer. In Stage IV, cancer may have spread to nearby lymph nodes and has spread to other parts of the body, such as the liver or lungs.

Recurrent colon cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the colon or in other parts of the body, such as the liver or lungs.

Treatment

There are different types of treatment for patients with colon cancer. Treatment options depend on the following:

• The stage of the cancer.
• Whether the cancer has recurred.
• The patient's general health.

Colon cancer is generally diagnosed by a gastroenterologist or general surgeon. Surgeons perform 1/3 of colonoscopies and gastroenterologists the remainder. Staging and treatment can be done by a general surgeon (diagnosis and/or surgical treatment), gastroenterologist (diagnosis and management), radiologist (diagnosis and/or staging) and oncologist (chemotherapy and radiation treatment and disease management).

Three types of standard treatment are used: surgery, chemotherapy and radiation therapy. An interesting additional treatment is psychotherapy. Kuchler et al. (2007) observed longer survival in patients with gastro-intestinal cancers after an average of 4 hours of individual, bed-side psychotherapeutic support in the peri-operative period.

Longer survival in gastrointestinal cancer after psychotherapeutic support. Source: Kuchler et al. 2007

More information about psychological factors and cancer can be found under Psycho-Oncology.

Surgery

Surgery (removing the cancer in an operation) is the most common treatment for all stages of colon cancer. A doctor may remove the cancer using one of the following types of surgery:

• Local excision: If the cancer is found at a very early stage, the doctor may remove it without cutting through the abdominal wall. Instead, the doctor may put a tube through the rectum into the colon and cut the cancer out. This is called a local excision. If the cancer is found in a polyp (a small bulging piece of tissue), the operation is called a polypectomy.
• Resection: If the cancer is larger, the doctor will perform a partial colectomy (removing the cancer and a small amount of healthy tissue around it). The doctor may then perform an anastomosis (sewing the healthy parts of the colon back together). The doctor will also usually remove lymph nodes near the colon and examine them under a microscope to see whether they contain cancer.

Three panel drawing showing colon cancer surgery with anastomosis; first panel shows area of colon with cancer, middle panel shows cancer and nearby tissue removed, last panel shows cut ends of colon joined.Colon cancer surgery with anastomosis. Part of the colon containing the cancer and nearby healthy tissue is removed, and then the cut ends of the colon are joined.Source:NCI

• Resection and colostomy: If the doctor is not able to sew the two ends of the colon back together, a stoma (an opening) is made on the outside of the body for waste to pass through. This procedure is called a colostomy. A bag is placed around the stoma to collect the waste. Sometimes the colostomy is needed only until the lower colon has healed, and then it can be reversed. If the doctor needs to remove the entire lower colon, however, the colostomy may be permanent.

Three panel drawing showing colon cancer surgery with colostomy; first panel shows area of colon with cancer, middle panel shows cancer and nearby tissue removed and stoma created, last panel shows a colostomy bag attached to the stoma.Source:NCI

• Radiofrequency ablation: The use of a special probe with tiny electrodes that kill cancer cells. Sometimes the probe is inserted directly through the skin and only local anesthesia is needed. In other cases, the probe is inserted through an incision in the abdomen. This is done in the hospital with general anesthesia.
• Cryosurgery: A treatment that uses an instrument to freeze and destroy abnormal tissue, such as carcinoma in situ. This type of treatment is also called cryotherapy.

Even if the doctor removes all the cancer that can be seen at the time of the operation, some people may be given chemotherapy or radiationtherapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to increase the chances of a cure, is called adjuvant therapy.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy).

• Chemoembolization of the hepatic artery may be used to treat cancer that has spread to the liver. This involves blocking the hepatic artery (the main artery that supplies blood to the liver) and injecting anticancer drugs between the blockage and the liver. The liver's arteries then deliver the drugs throughout the liver. Only a small amount of the drug reaches other parts of the body. The blockage may be temporary or permanent, depending on what is used to block the artery. The liver continues to receive some blood from the hepatic portal vein, which carries blood from the stomach and intestine.

The way the chemotherapy is given depends on the type and stage of the cancer being treated.

Radiation Therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.

New types of treatment are being tested in clinical trials. These include the following:

Biologic therapy is a treatment that uses the patient's immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body's natural defenses against cancer. This type of cancer treatment is also called biotherapy or immunotherapy.

After treatment, a blood test to measure carcinoembryonic antigen (CEA; a substance in the blood that may be increased when colon cancer is present) may be done along with other blood tests to monitor cancer recurrence. Follow-up exams may help find recurrent colon cancer earlier.

Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. Before starting treatment, patients may want to think about taking part in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or to obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Treatment by Stage

Treatment of stage 0 (carcinoma in situ) may include the following types of surgery:

• Local excision or simple polypectomy.
• Resection /anastomosis. This is done when the tumor is too large to remove by local excision.

Check for clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage 0 colon cancer.

Treatment of stage I colon cancer usually involves resection /anastomosis.

Check for clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage I colon cancer.

Treatment of stage II colon cancer may include the following:

• Resection /anastomosis.
• Clinical trials of chemotherapy, radiation therapy, or biologic therapy after surgery.

Check for clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage II colon cancer.

Treatment of stage III colon cancer may include the following:

• Resection /anastomosis with chemotherapy.
• Clinical trials of chemotherapy, radiation therapy, and/or biologic therapy after surgery.

Check for clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage III colon cancer.

Treatment of stage IV and recurrent colon cancer may include the following:

• Resection /anastomosis (surgery to remove the cancer or bypass the tumor and join the cut ends of the colon).
• Surgery to remove parts of other organs, such as the liver, lungs, and ovaries, where the cancer may have recurred or spread.
• Radiation therapy or chemotherapy may be offered to some patients as palliative therapy to relieve symptoms and improve quality of life.
• Clinical trials of chemotherapy and/or biologic therapy.

Treatment of locally recurrent colon cancer may be local excision.

Special treatments of cancer that has spread to or recurred in the liver may include the following:

• Chemotherapy followed by resection.
• Radiofrequency ablation or cryosurgery.
• Clinical trials of hepatic chemoembolization with radiation therapy.

Patients whose colon cancer spreads or recurs after initial treatment with chemotherapy may be offered further chemotherapy with a different drug or combination of drugs.

Check for clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage IV colon cancer and recurrent colon cancer.

Prognosis

Source: Surveillance, Epidemiology and End Results (SEER) ^[2]

The prognosis (chance of recovery) from colon cancer depends on the following factors:

• The stage of the cancer (whether the cancer is in the inner lining of the colon only, involves the whole colon, or has spread to other places in the body).
• Whether the cancer has blocked or created a hole in the colon.
• The blood levels of carcinoembryonic antigen (CEA; a substance in the blood that may be increased when cancer is present) before treatment begins.
• Whether the cancer has recurred.
• The patient's general health.

For more comprehensive information about incidence and mortality for colon cancer, see the National Cancer Insitute's SEER (Surveillance Epidemiology and End Results) Cancer Stat Fact Sheet: Cancer of the Colon and Rectum.

Living with Colon Cancer

Close follow up after treatment is very important. Most recurrences of colorectal cancer occur in the first five years after diagnosis. Follow-up for Stage II and III cancers, for example, is done every three to six months for 3 years, then every 6 months until five years post-diagnosis. Follow-up is important in order to find recurrences as early as possible and to provide reassurance about the lack of recurrence. Follow-up tests generally consist of CEA levels, colonoscopy and CT scans.

The support of family and friends is essential after a diagnosis of colon cancer. The Colon Cancer Alliance has an article titled Information for People Living with CRC (Colorectal Cancer) that may help with finding support from a variety of sources.

Support groups may also be helpful after diagnosis. The Colon Cancer Alliance has groups and events listed as does the National Cancer Institute.

The American Cancer Society has a guide titled What Should You Ask Your Doctor About Colorectal Cancer? and another called What Happens After Treatment? that may be helpful for someone faced with a diagnosis of colon cancer.

Chances of Developing Colon Cancer

Risk Factors

Anything that increases the chance of getting a disease is called a risk factor. Having a risk factor does not mean that a person will get cancer. On the other hand, not having risk factors doesn't mean that a person will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for colon cancer include the following:

• Age 50 or older.
• A family history of cancer of the colon or rectum.
• A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.
• A history of colon polyps.

Colon polyps; shows two polyps (one flat and one pedunculated) inside the colon. Inset shows photo of a pedunculated polyp.Polyps in the colon. Some polyps have a stalk and others do not. Inset shows a photo of a polyp with a stalk; Source:NCI ^[3]

• A history of inflammatory bowel disease(IBD),ulcerative colitis (ulcers in the lining of the large intestine) or Crohn's disease.
• Certain hereditary conditions, such as familial adenomatous polyposis, hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome), and Peutz-Jeghers syndrome
• Race (African-Americans have a higher incidence of colon cancer for unknown reasons) and ethnicity (as do Ashkenazi Jews because of a genetic mutation)
• Lifestyle choices such as:
  • High-fat diet or a diet rich in processed meats
  • Obesity
  • Smoking
  • Physical inactivity
  • Type 2 Diabetes

It is vitally important that everyone is screened for colon cancer using one or more of the methods described in the "diagnosis" section. People without symptoms and no significant risk factors for colorectal cancer should be screened starting at age 50. If risk factors are present, they should be discussed with a physician to determine when screening should begin. Follow-up screening depends on risk factors and any significant findings on initial screening tests.

Incidence

Incidence: according to the American Cancer Society, it is expected that there will be 10,070 new cases of colon cancer and 40,740 cases of rectal cancer diagnosed in the U.S. in 2008. Half the cases will be diagnosed in women, half in men. Colon cancer is the third most common cancer in men and women. The number of deaths from colon and rectal cancer will be approximately 49,960 - again half of each gender. This represents 9% of the total deaths from cancer in the U.S.

The incidence of colon cancer death has decreased over the past twenty years, especially over the past several years. This decrease is due to incresed screening of colon cancer, earlier detection and better treatment options.

Research

There is some recent exciting research in the field of colorectal cancer. Some recent developments:

• A scientist at Emory University in Atlanta is developing a biomarker screening blood test for colon cancer . The test would not eliminate the need for colonoscopy screening but may be able to better target who needs to be screened, at what age, and how often.

• In a recent study, researchers at Case Western University have identified a gene linked to the development of colon cancer .

• Genomic Health, Inc. recently announced that they have identified genes that could help predict the likelihood of recurrence and chemotherapy benefit for early-stage (stage II and III) colon cancer. More research and validation is ongoing.

• The journal Gastroenterology recently published an article titled Diet High in Meat, Fat, and Refined Grains Is Associated With Increased Risk for Colon Cancer Recurrence and Death^[4]

• Gastroenterology also published Sporadic Colorectal Cancer: An Infectious Disease?^[5] which supports a possible role for the bacteria Enterococcus faecalis in the development of colon cancer.

• The American Society for Gastrointestinal Endoscopy references a March 5, 2008 article in JAMA in their press release (3/6/08) titled Colonoscopy Used to Identify and Remove Flat Colon Lesions: Flat Colon Lesions More Common and More Likely to be Cancer According to JAMA Study

Colon Cancer in the News

Colon cancer has been in the news a great deal over the past several years. Katie Couric, who lost her husband to the disease in 1998, has become a vocal advocate for colon cancer awareness and screening. She even had a colonoscopy live on national television in March of 2000.

U.S. News and World Report ran the following article about screening for colon cancer in March 2008.

For other recent news articles about colon cancer, the Colorectal Cancer Coalition has a summary at All News in Colorectal Cancer

Interesting Facts

Famous people

Celebrities who have been treated for colon cancer include:

• Former U.S. president Ronald Reagan
• Former White House press secretary Tony Snow
• Film critic Joel Siegel
• Sharon Osbourne
• Baseball greats Darryl Strawberry and Eric Davis

Celebrities who have died from colon cancer include:

• Film critic Joel Siegel
• Audrey Hepburn
• Peanuts cartoonist Charles Schulz

Related Videos

Everyone responds differently to medicines. The dose of a drug that cures one person can be ineffective-or even toxic-in someone else. Although many non-genetic factors play a role in how an individual patient responds to a particular drug treatment, many differences in drug response come from genetic variation. Individualizing a drug's dose based on pharmacogenomic information can help a patient get the most benefit from a drug while minimizing side effects.

References

1. ↑ Picelli S, Vandrovcova J, Jones S, et al. Genome-wide linkage scan for colorectal cancer susceptibility genes supports linkage to chromosome 3q. BMC Cancer. 2008 Apr 1;8:87. Full Text
2. ↑ http://seer.cancer.gov/
3. ↑ http://www.cancer.gov/cancertopics/pdq/treatment/colon/patient
4. ↑ L. Lang. Diet High in Meat, Fat, and Refined Grains Is Associated With Increased Risk for Colon Cancer Recurrence and Death]. Gastroenterology 2007 133(4): Page 1063. Full Text
5. ↑ F.A. Sinicrope. Sporadic Colorectal Cancer: An Infectious Disease? Gastroenterology. 2007 132(2): Pages 797-801. Full Text

Küchler T, Bestmann B, Rappat S, Henne-Bruns D, Wood-Dauphinee S.Impact of psychotherapeutic support for patients with gastrointestinal cancer undergoing surgery: 10-year survival results of a randomized trial.J Clin Oncol. 2007 Jul 1;25(19):2702-2708. Pubmed abstract: [1]

External Resources

The National Cancer Insitute (NCI) has various resources:

The NCI Web site provides online access to information on cancer, clinical trials, and other Web sites and organizations that offer support and resources for cancer patients and their families.

The American Cancer Society has a page called Additional Resources with a wealth of information about colon cancer.

American Cancer Institute: Colon and Rectal Cancer

American Society of Clinical Oncology: Colorectal Cancer Patient Guide

Psychomedical Help [2] gives a descrption of psycho-oncology research and related subjects.