Colon Cancer

Colon cancer is diagnosed and treated by the GI Division of Premier Medical Group.

What is colon cancer?

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Colon cancer forms in the large intestine (colon), which is the lower part of your digestive system. It is the second leading cause of cancer deaths in the US. When found in its early stages, colorectal cancer is highly treatable.  In many cases, colorectal cancer can be prevented.

According to the American Cancer Society, the rate of new colorectal cancer cases and deaths from the disease has been shrinking by about 2% a year over the last decade. To a large extent, this is because more people are receiving periodic colorectal cancer screenings.

Wha are the causes of colorectal cancer?

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Most colorectal cancers begin as tiny clumps of abnormal cells on the lining of the colon or rectum, called adenomatous polyps. These polyps are benign (non-cancerous), but have the potential to become malignant (cancerous). The transformation is slow-occurring over several years and the polyps usually produce no recognizable symptoms to alert patient and doctor.

People who develop numerous adenomatous polyps have a greater-than-normal risk of colorectal cancer. This is referred to as adenomatous polyposis syndrome, and tends to run in families. Such cases are called familial adenomatous polyposis (FAP). The cancer usually occurs before age 40.

Another possible cause for colorectal cancer is called hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, which also runs in families. In this type, colon cancer can develop without polyps.

Researchers have determined that the HNPCC syndromes are associated with a genetic abnormality. They have identified the gene and people at risk can be identified genetic screening. Once a person is determined to carry the abnormal gene, counseling is recommended along with regular screenings for cancerous tumors.

Other causes that put people at risk for colorectal cancer can be:

  • Ovarian, breast or uterine cancer
  • Ulcerative colitis
  • Crohn’s Disease
  • Family history (risk increases 2-3 times for people with an immediate family member, especially if the cancer was found at an early age. There is an even greater risk when more than one family member is affected with colon cancer)
  • A diet lacking in high fiber, fruits, and vegetables
  • Obesity
  • Smoking

What are the symptoms of colorectal cancer?

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Colorectal cancer does not always show symptoms. Beginning at age 45, and earlier if there is a family history, it is very important to have regular examinations, called colorectal screenings, or colonoscopies.

An early symptom of colorectal cancer may be rectal bleeding, and sometimes in only small amounts which can only be found in stool specimen testing.

Other symptoms may include:

  • Stools that look narrower or thinner than normal
  • A change in bowel habits, diarrhea or constipation that lasts more than a couple of weeks
  • Bright red or very dark blood in the stool; black stools
  • Fatigue
  • Unexplained weight loss
  • Anemia
  • Vomiting
  • Feeling that bowel is not completely empty when having a movement
  • Unusual stomach or gas pain, sometimes mistaken for pancreatitis symptoms

If you experience any of these symptoms, it is vital to see your health care provider as soon as possible to guarantee proper diagnosis and treatment. When colorectal cancer is found in the early stages, treatment can be very effective.

How is colorectal cancer diagnosed?

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The first step to a diagnosis is a complete medical history. This may include a digital rectal exam. At this time he or she may take a stool sample and check it for blood.  If your health care provider finds concerning symptoms, the next step would be to schedule a diagnostic workup. This may include:

  • Colonoscopy: A slender flexible tube which has a video camera attached to it is inserted in the rectum and the entire length of the colon. When a polyp is found, surgical instruments are deployed through the colonoscope to remove it take a tissue sample for testing (biopsy). You must prep before this exam. It is recommended that men and women should begin screening for colorectal cancer at age 45 and that the exam should be repeated every 5-10 years, depending on the findings. People with a family history should discuss their screening recommendations with their doctor.
  • Sigmoidoscopy: This is a small probe with a camera and light. The difference between this and the colonoscope is that the sigmoidscope only reaches the large colon.  Biopsies can be taken with this scope as well
  • Blood tests: A blood test at a lab or in your doctor’s office can provide a good picture of your general health. If you have a history of colon cancer, the doctor may order a special blood test called a CEA (carcinoembryonic antige) which can help identify returning tumors.
  • Diagnostic imaging tests: An imaging test is painless and usually does not need any preparation (unless it’s a barium enema). These include CT scans, rectal ultra- sounds, X-Rays, and MRIs (magnetic resonance imaging).
  • Biopsy: When the doctor takes a small tissue sample from your intestines, or removes a polyp and sends it to a lab for analysis, this is called taking a biopsy.  Colon biopsies can be completed during colonoscopies, sigmoidoscopies, or during a CT scan-guided needle biopsy. Biopsy results can take from 72 hours to a week for processing. Ask your doctor when to expect results.

By the time colorectal cancer is diagnosed, it has often been growing for several years, first as a non-cancerous polyp (adenoma) and later as cancer. Research indicates that by age 50, one in four people has polyps.

What are the types of colorectal cancer?

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Adenocarcinomas are the most common type of colon cancer. This type of cancer originates in the glands and accounts for about 90-95 percent of colorectal cancers.  There are two sub-types, mucinous and signet ring cell. The mucinous subtype comprises about 10-15 percent of adenocarcinomas while the signet ring cell subtype comprises less than 0.1 percent of adenocarcinomas. The bigger the gland (adenoma), the more probable it is to become cancerous. If your doctor finds a polyp larger than two centimeters (size of a nickel) it is more likely to be cancerous than a much smaller polyp.

Leiomyosarcoma is a type of colon cancer that develops in the smooth muscle of the colon. Although this type is responsible for less than 2 percent of colorectal cancers, it has a fairly high chance of metastasizing.

Lymphomas are the rarest in the colon cancer family. They generally originate in the rectum rather than the colon, but if they begin in another part of the body, they are likely to spread to the colon.

Melanoma is rare as a colon cancer. Melanoma commonly begins in another area of the body and can end up spreading to the colon, but rarely begins there.

Tumors can be idle or they can be aggressive. Large and small cell (neuroendocrine) tumors are aggressive and (carcinoid) tumors are lazy or idle.

Other factors that may affect getting colon cancer are:

  • Obesity
  • Diet (some researchers believe that eating a high fiber, low fat diet may help prevent colon cancer, but its remains under debate)
  • Smoking
  • Drug effects (some studies suggest that aspirin and estrogen replacement therapy may reduce your risk)

What are the treatment options for colon cancer?

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There are four types of treatment available for colon cancer:

Surgery: the primary treatment of colon cancer, is the removal of all or part of the colon (polyps are generally removed during colonoscopy). There are several types of surgical procedures that the doctor will consider, depending on the stage of the colon cancer.

Resection: This is done when the cancer is large, and he or she removes the cancerous portion of the colon along with some healthy tissue around it (colectomy). The two ends are then attached together. At this time the lymph nodes may also be removed.

Colostomy: If the doctor is unable to attach the two ends together, a stoma or opening is made on the outside of the body for waste to pass through.  A bag is attached and is emptied by the patient. In some cases the colostomy can be reversed.

Local excision: When the cancer is found very early, the doctor may be able to remove it by putting a tube through the rectum, into the colon and cutting it out.

Chemotherapy: also known as chemo, is a term used by doctors to refer to a class of drugs (antineoplastic drug or a combination of such drugs) that work by killing off fast growing cancer cells, but it can’t always tell the difference between cancer cells and fast growing healthy cells.  This results in low blood counts (both red and white), and because of this, makes the patient vulnerable to infections. This is a powerful tool in fighting many types of cancers.

Chemo can be administered in three ways:

  • Orally in pill form
  • Intravenously by injection
  • Intravenously with a pump

There are two types of chemotherapy: Adjuvant, and Neoadjuvant. Adjuvant is administered after cancer is removed, to kill any cancer cells that may have been missed. Neoadjuvant is given before surgery to shrink any tumors so the surgeon is able to remove it with fewer complications.

Radiation is a powerful tool that can be used to treat colon cancer and it is also used to treat rectal cancer. When used before surgery, radiation can reduce the size of any tumors. This treatment uses high-energy x-rays or other types of radiation to stop any cancer cells from growing.

Targeted therapy is the use of particular drugs that identify and attack specific cancer cells. This type of therapy does not harm the normal cells.

Monoclonal antibody therapy is also a targeted type of therapy. It isolates proteins which are specific to colon cancer and targets them.

Radiofrequency ablation is when the surgeon uses a very specialized probe. This probe has small electrodes that will kill the cancer cells. The probe can be inserted through an incision in the groin or abdomen and is performed in the hospital under general anesthesia. If it’s inserted into the skin, it can be done with a local anesthetic.

Cryosurgery is a type of treatment that is used to freeze and kill cancerous tissue.

FAQs about colon cancer

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Q: When should I seek medical care?

A: If you notice any of the following symptoms, you should see your health care provider as soon as possible.

  • Change is bowel habits, frequency or consistency
  • Unusual abdominal pain, discomfort or distension
  • Bright red blood on the toilet paper, on your stool, or in the toilet
  • Unexplained weight loss, nausea, vomiting
  • Feeling of incomplete bowel movement
  • Rectal bleeding
  • Severe pain in belly or groin


Q: Will folic acid help prevent colon cancer?

A: Folic acid is a water-soluble vitamin that is often added to cold cereals, flour, breads, pasta, bakery items, cookies, and crackers. Some studies believe that by taking folic acid supplements it could lower the risk of colon cancer, but it does not seem to help patients who have already been diagnosed with the disease.


Q: What are the stages of colon cancer?


  • Stage 0: Very early cancer on the innermost layer of the intestine
  • Stage I: Cancer is in the inner layers of the colon
  • Stage II: Cancer has spread through the muscle wall of the colon
  • Stage III: Cancer has spread to the lymph nodes
  • Stage IV: Cancer has spread to other organs


Q: What is an adenoma?

A: It is a benign or non-cancerous polyp or growth in the lining of the large intestine. They can be signs of colon and rectal cancer.


Q: Can diet affect colon cancer?

A: The best way to avoid colon cancer is by eating a high-fiber, low fat diet, and by maintaining a healthy body weight by keeping active.


Q: Does blood in my stool mean I have colon cancer?

A:  While early signs of colon cancer can be rectal bleeding, there are other reasons such as hemorrhoids which can cause blood in your stool. The most important thing you can do is get a proper diagnosis.