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Symptoms and Tests: Colon Cancer


Symptoms of colorectal cancer include:

If these symptoms occur a patient should see their health care provider to discuss getting screened.

Diagnosis of Colon Cancer

The goal of colorectal cancer screening is to remove precancerous polyps before they develop into cancer or to diagnose a cancer in its early stages when survival is greatest. See this NetWellness feature for more information on recommended cancer screening strategies. In this section you will find information on:


Accepted screening methods have recently emphasized colonoscopy. A colonoscopy is a noninvasive means of directly examining the lining of the entire colon and distal portion of the small bowel. It may be ordered for colorectal cancer screening or to investigate the cause of a patient’s bright red blood or black tarry stools, unintentional weight loss, abdominal pain, unexplained diarrhea or constipation, or fatigue due to anemia.

Preparing for colonoscopy

The quality of the information gained from a colonoscopy is directly related to a patient’s preparation prior to arriving the day of the procedure.

What to do one week before the procedure

  1. If the patient is taking medications such as aspirin, ibuprofen, naprosyn, clopidogrel (Plavix), or warfarin (Coumadin), they should call their primary care physician, at least one week prior to the procedure date, to see if it is safe to stop these medications.
  2. Iron supplements must be stopped five days prior to the procedure.
  3. If the patient is diabetic, the patient should contact their primary care provider for instructions on how to take their oral medications and insulin during the day prior to the procedure as well as during the day of the procedure.
  4. The patient should also arrange for a driver to transport them to and from the procedure.

What to do the day before the procedure

In order to visualize the lining of the colon, it is important to clear the colon of stool. This is done by the patient altering their diet and by taking a strong laxative. The day prior to the procedure, the patient should eat no solid food. Liquids are allowed, but are limited to clear liquids without red coloring including:

  • gingerale
  • plain coffee (without cream or milk)
  • fat-free buillone or broth
  • popsicles
  • Jell-O
  • Laxative options:
  • Electrolyte balanced liquid laxative

About oral laxatives

The most common is an oral laxative which is electrolyte balanced with polyethylene glycol to avoid interfering with electrolyte concentrations in the blood. The standard medications of this type are Golytely, Nulytely, and Colyte. The 2-4 liters of solution should be consumed in 4-6 hours. In general, this solution is not pleasant tasting and flavors have been added to mask the taste. Although this type of preparation has a larger volume, it does have added benefits in not causing preparation related ulcerations in the colon or electrolyte imbalances in the blood.

An alternative is the use of MiraLax, which is an over-the-counter laxative that is tasteless and can be mixed with 2 liters of any clear liquid. Many physicians are now using a “split dose” bowel preparation, in which half of the laxative is taken the morning of the procedure. This type of preparation is often associated with more satisfactory results.

Sodium phosphate tablet laxative

Patients who are used to taking a lot of oral medication may prefer a sodium phosphate tablet preparation called Visicol or OsmoPrep. However, a total of 20-32 pills are taken the night prior to and repeated the day of the procedure. Patients with a history of kidney disease, chronic liver disease, congestive heart failure, electrolyte abnormalities or suspected inflammatory bowel disease should not take this medication.

Other combinations of laxatives and dietary restriction may need to be considered if the patient cannot tolerate the above preparations.

What you can expect the day of the test

The day of the procedure, the patient will arrive at the endoscopy suite. An IV will be placed for medication administration. The gastroenterologist (endoscopist) will speak to the patient.

The patient should notify the endoscopist of:

  • their medical history
  • if they receive antibiotics prior to a dental procedure
  • if they have a pacemaker
  • if they have a defibrillator
  • any medications they are taking – it’s best to provide a list

After a short conversation, the patient will sign the consent form and the sedation medications will be given.

Once the patient is sedated, the endoscopist will perform a rectal exam and insert the colonoscope which is a long flexible tube approximately the diameter of an index finger with a camera lens and light. The colonoscope will be advanced to the farthest part of the colon and possibly into the small bowel. The physician can see the images on a television screen.

Biopsies of the colonic tissue may be taken or polyps may be removed. This is done using forceps or a snare loop to lasso the polyp. The area may then be cauterized to prevent heavy bleeding. During the procedure the patient may feel abdominal pressure from air pumped into the colon. This is necessary to help the doctor to better see the colon. There may also be brief periods of abdominal pain if there are sharp turns in the colon. Patients will not feel the biopsy or polyp removal.

After the procedure, the patient may feel abdominal bloating but this will improve as the patient expels the remaining air that was pumped in during the procedure. As with any procedure there are potential complications but these are very rare. They may include bleeding, infection, adverse reaction to the sedation medications, or a tear in the bowel wall (perforation) which could require surgery.

After the procedure, the patient will be monitored in the recovery area for 30 minutes to an hour and then be driven home by their driver. Prior to discharge the patient should have a discussion with the physician regarding the test findings. It may be helpful for the driver to be privy to this conversation since the patient may forget the conversation due to the sedation medications. During this time, if the patient stopped aspirin, motrin, plavix or coumadin they should ask the physician when it is safe to restart these medications. Pathology results from biopsies or polyp removal should be available within 1 week.

If the patient has fever, a distended firm abdomen, severe abdominal pain (not gas cramps), bloody bowel movements greater than a half cup in volume, nausea or vomiting, they should call the endoscopist or the physician on call and may need to be evaluated.

Follow up of Colon Cancer 

If the entire colon was not visualized by colonoscopy prior to surgery, a colonoscopy will need to be performed within six months after surgery. Assuming this does not reveal another cancer, or the first colonoscopy was complete, it is recommended that a patient have a colonoscopy one year after surgery to detect new polyps or tumors. CEA monitoring is also recommended in follow-up. In addition, office visits at least three times a year for the first two years are recommended because symptoms are often the first indicator of cancer recurrence.

Determining the Stage of Colon Cancer

Every cancer is tested to determine how advanced it is. This is called staging. Each stage is given a numerical value. The larger the number, the more advanced the cancer.

Staging of colorectal cancer will help to determine the best treatment strategy, and to predict long-term survival rate. Staging consists of determining if the tumor has metastasized to other organs or lymph nodes, and if it has spread into the deeper layers of the bowel wall. Preoperative staging usually consists of an abdominal CT scan and possibly, a chest X-ray or chest CT scan. Prior to surgery, a blood sample may be sent to determine the level of a tumor marker known as carcinoembryonic antigen (CEA), which may be useful in monitoring for recurrence.

Rectal cancer staging consists of a CT scan of the abdomen and pelvis, and an X-ray or CT scan of the chest because unlike colon cancer, rectal cancer has a different blood supply and can travel to the lungs, bypassing the liver. Regional lymph node and tumor wall depth can be assessed by Magnetic Resonance Imaging (MRI) or endoscopic ultrasound which is similar to the colonoscopy, yet only requires an enema preparation and examines only the rectum using sound waves. Depending on how close the tumor is to the anus and how deep the tumor has spread, the surgeon may chose a transanal, abdominoperitoneal or low anterior resection.

The stages of cancer are defined as follows:

Stage 0 – Superficial extension

Stage 1 – Extension into colon wall (submucosa)

Stage 2 – Extension deeper into muscular layer (muscularis propria)

Stage 3 – Lymph node involvement

Stage 4 – Distant metastasis

More features about colon cancer:

For more information:

Go to the Colon Cancer health topic.