What is colorectal carcinoma?
Colorectal carcinoma is a cancer, or malignant tumor, of the large intestine, which may affect the colon or rectum. Typically, the colon is the upper five or six feet of the large intestine, and the rectum is the lower five to seven inches located above the anal canal.
Factors such as age, race, personal or family history of colon disease and diet can play a significant role in having an increased risk of developing colorectal cancer.
Many colon cancers develop over a long period of time, often arising from pre-cancerous colon polyps which gradually grow and may turn into cancer slowly. Many early stage colon cancers do not cause any symptoms at all. Therefore, various methods of colon cancer screening are currently recommended and conducted in the hopes of finding the polyp or cancer at a time when it can be removed and cured. You should consider talking to your physician about if and when you may be eligible for colon cancer screening.
If the cancer has grown to a size where it causes symptoms, these may include:
- Abdominal pain, cramps or gas
- Weight loss
- Changes in bowel movements such as diarrhea, constipation or bloating
- Blood in the stool or rectal bleeding
- Partial or complete blockage of bowel passage
How is colorectal carcinoma diagnosed and evaluated?
In order to diagnose the cause of symptoms, your doctor may order:
- Colonoscopy: This examination uses a flexible tube with a tiny camera at the end, which is inserted into the colon. The camera captures images of the interior of the large intestine.
- CT Colonography (www.radiologyinfo.org/en/info.cfm?pg=ct_colo): A small tube is inserted into the rectum and air is pumped into the colon. Then, low dose CT images of the abdomen and pelvis are obtained with the patient on their lying on their back and then stomach. Software can then create a three-dimensional (3-D) interior view of the colon, allowing specially trained radiologists to look for abnormalities (like polyps or cancer) in the large intestine.
- Air-contrast barium enema (www.radiologyinfo.org/en/info.cfm?pg=lowergi): This x-ray exam of the large intestine allows radiologists to view the colon and rectum in real-time and detect any abnormal growths.
Other types of imaging exams that your doctor may order include:
- Abdominal and Pelvic CT (www.radiologyinfo.org/en/info.cfm?pg=abdominct): This imaging procedure uses x-rays to quickly identify sources of pain or abnormalities within the gastrointestinal tract.
For more information about CT exams performed on children, visit the Pediatric CT page (www.radiologyinfo.org/en/info.cfm?pg=pedia-ct).
- PET/CT (www.radiologyinfo.org/en/info.cfm?pg=PET): Positron emission tomography (PET) is a type of nuclear medicine scan that uses a small amount of radioactive material to image body functions. A PET/CT exam fuses images from PET and CT scans to detect and anatomically localize cancer and determine the amount of cancer spread.
- Magnetic Resonance Imaging (MRI) of the Body (www.radiologyinfo.org/en/info.cfm?pg=bodymr): This imaging test uses a magnetic field and radio frequency pulses to produce detailed pictures of the internal organs and is helpful for detecting diseases of the small intestine, colon, rectum and anus. No radiation is involved.
- Endorectal Ultrasound: This imaging test uses high frequency sound waves generated from a probe, which is inserted into the rectum. The sound waves create a picture of the rectal wall and surrounding tissue. No radiation is involved. This test may be used to determine the local extent of disease if the patient has been diagnosed with rectal cancer.
How is colorectal carcinoma treated?
Depending on the size and extent of spread of the cancer, patients may need to undergo a surgery, removing part or all of the colon, in order to remove the tumor. For some patients, an ileostomy or colostomy may be needed, which diverts bowel content into an external bag. Advanced cases may require radiation therapy treatments such as:
- External Beam Therapy (EBT) (www.radiologyinfo.org/en/info.cfm?pg=ebt): This treatment is a form of radiation therapy done by aiming several beams or high-energy x-rays directly at a patient’s tumor. These x-rays deliver radiation to the patient’s tumor in order to destroy the cancer cells while leaving the surrounding healthy tissues unaffected.
In most cases, chemotherapy may be used as supplemental treatment. Chemotherapy is often given to decrease the chance of the tumor returning elsewhere in the body or to decrease the disease burden elsewhere in the body if it cannot be removed surgically. It is usually given over time and alternated with periods of no treatment. This alleviates potential side effects, such as abnormal blood-cell counts, fatigue, diarrhea, mouth sores, and a compromised immune system.
Locate an ACR-accredited provider: To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.
Exam costs: The costs for specific medical imaging tests and treatments vary widely across geographic regions. Many—but not all—imaging procedures are covered by insurance. Discuss the fees associated with your medical imaging procedure with your doctor and/or the medical facility staff to get a better understanding of the portions covered by insurance and the possible charges that you will incur.
Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of North America (RSNA), comprising physicians with expertise in several radiologic areas.
Outside links: For the convenience of our users, RadiologyInfo.org provides links to relevant websites. RadiologyInfo.org, ACR and RSNA are not responsible for the content contained on the web pages found at these links.
Images: Images are shown for illustrative purposes. Do not attempt to draw conclusions or make diagnoses by comparing these images to other medical images, particularly your own. Only qualified physicians should interpret images; the radiologist is the physician expert trained in medical imaging.
This page was reviewed on January 02, 2013