Colorectal cancer is the second most common cancer in the United States, affecting 140,000 new patients every year and responsible for 60,000 deaths a year. These are a very upsetting numbers, especially if you consider the fact that colorectal cancer is potentially curable if diagnosed in the early stages. The average person's lifetime risk of developing colorectal cancer is about one in 20.

Colorectal cancer is known as a "silent" disease, because many people do not develop symptoms, such as rectal bleeding, abdominal pain or change in the usual pattern of bowel movements, until the cancer reaches an advanced stage and is therefore difficult to treat. In fact, the possibility of curing patients after symptoms develop is only about 50%.
The risk is increased if there is a family history of colorectal polyps or cancer, and is still higher if there is a personal history of breast, uterine or ovarian cancer. Risk is also higher for people with a history of extensive inflammatory bowel disease, such as ulcerative or Crohn's colitis.
The American Cancer Society, the American Society of Colon and Rectal Surgeons, as well as other Society uniformly recommend that every individual be enrolled in a screening protocol at age 50, as long as he does not fall in any of the high risk categories.
Screening means that the physician actively looks for cancer in patients that have no symptoms whatsoever. The advantage of screening is that cancers are usually detected very early; colorectal cancers found and treated at an early stage, which is before symptoms develop, the opportunity to cure is 80% or better. Most colon cancers start as non cancerous growths called polyps. If the polyps are removed, then the cancer may be prevented altogether and surgery can usually be avoided.  It has been shown over and over that those cancers that are detected by screening are more often curable than those cancers that already showed symptoms, such as bleeding or diarrhea.
Surveillance involves testing people who have previously had colorectal cancer or are at increased risk. Because their chance of having cancer is higher, more extensive or more frequent tests are recommended. The most common surveillance protocols will be discussed later.
 
Screening:
The screening tools for average risk patients consist of:

• A. The combination of occult blood testing of the stool, a digital rectal exam and a flexible sigmoidoscopy .
• B: The combination of Air Contrast Barium Enema and flexible sigmoidoscopy .
• C: A Complete Colonoscopy.
• D: A Virtual Colonoscopy.

A. Combination of occult blood testing of the stool, a digital rectal exam and flexible sigmoidoscopy . The advantage of fecal occult blood testing is low cost and ease of performance. Unfortunately, the fecal occult blood testing gives often false positive and false negative results, which means that it may miss some of the colon and rectal cancers or it may be positive in people that do not have the disease. In order to decrease the risk of false negative results the fecal occult blood testing is performed 3 times on 3 consecutive days; false positive results may be minimized by following certain dietary restrictions before and during the collection of the stool specimen.
If the Fecal occult blood test is negative the screening should be completed by performing a flexible fiberoptic sigmoidoscopy. This is an endoscopic procedure that allows direct visualization of the distal 2 feet of large bowel, which is the rectum and the sigmoid colon.
If the Fecal occult blood test is positive the screening should be completed by performing a colonoscopy. 

B Combination of Air Contrast Barium Enema and flexible sigmoidoscopy. This approach has the disadvantage of combining two tests that are uncomfortable and have only diagnostic capabilities; if any of the two tests shows a polyp, then a colonoscopy needs to be performed in order to remove it. In the worst case scenario a patient may have a negative sigmoidoscopy, a polyp detected by ACBE in the proximal colon and eventually required to have a full colonoscopy for polyp removal. The advantage of this approach is limited to those patients in which a colonoscopy would be extremely difficult or impossible because of  extensive intrabdominal adhesions, diverticular disease or anatomical abnormalities.

C Complete Colonoscopy. There is today enough evidence in the literature to support the fact that a full colonoscopy is the most sensitive and most cost effective test for colorectal cancer screening in the patients at average risk

D Virtual Colonoscopy is a radiological exam based on the use of Computerized Axial Tomography  technique (also known as CAT Scan). It is a strictly diagnostic tool (meaning that it is able to detect colorectal cancers and polyps), however has no therapeutic capabilities. Polyps detected by Virtual Colonoscopy still need to be removed through the use of a conventional colonoscopy.
 
Surveillance:
The patients that belong to a high risk categories, such as having a family history of colorectal cancer, or a personal history of ulcerative colitis or familial polyposis, need to be screened more thoroughly and more frequently. Patients that have a personal history of colorectal cancer successfully removed in the past or colorectal polyps also belong to the high risk category and should be evaluated endoscopically at regular intervals. The process in these cases is called surveillance, rather than screening

The surveillance tools for high risk patients consist of a colonoscopy or a combination of flexible sigmoidoscopy and air contrast barium enema. 

The most common surveillance protocols are as follows:

• A Personal history of Colorectal Cancer. Yearly colonoscopy for 2-3 year after the initial diagnosis, the every 2-3 years.
• B Personal history of Colorectal Polyps. Colonoscopy every 3 years, after the colon has been declared "polyp free".
• C Personal history of ulcerative colitis or Crohn's disease. Yearly colonoscopy after the ninth year from the actual beginning of the disease ( keep in mind that the actual beginning of the disease may be several years before the initial diagnosis of inflammatory bowel disease).
• D Family history of colorectal cancer. Colonoscopy  starting at an age 5 years younger then the age of diagnosis in the affected relative or at age 40, whichever occurs first. In order to qualify for "family history" the relative affected by colorectal cancer must be a "first degree blood relative". After an initial negative colonoscopy they follow the same protocol as average risk patients.
• E People with a family history of an inherited disease called familial adenomatous polyposis (FAP) should receive counseling and consider genetic testing to see if they are carriers for the gene that causes the disease. People with this gene or whose tests are inconclusive should have a flexible sigmoidocopy annually beginning at puberty to see if they are expressing the gene. If polyposis is present, they should discuss with their physician the need for total colectomy, which involves removing all the colon and rectum.
• F People with a family history of colorectal cancer in several close relatives and several generations, especially cancers occurring at a young age, should receive genetic counseling and consider genetic testing for a condition called hereditary nonpolyposis colorectal cancer. People with this family medical history should have an examination of the entire colon preferably colonoscopy every two years starting between the age of 20 and 30, and every year after age 40
• G Women with a personal history of breast or female genital cancer (ovary or uterine) have a 15% lifetime risk (1 in 6) of developing colon cancer. They should undergo colonoscopy every 5 years, beginning at age 40. 

Flexible sigmoidoscopy suite	Normal sigmoid colon