Colorectal Cancer Screening and Surveillance
The general principle behind colon cancer screening is the realization that most colon and rectal cancers start as visible polyps or growths within the colon. Over a variable time period, many polyps depending on type (usually adenomatous polyps) can progress to colon cancer if left untreated. Most polyps, especially those of small size, are usually asymptomatic (causing no symptoms or problems for the patient). Screening or testing for polyps and colon cancer in patients without symptoms attempts to find and remove polyps, thus positively impacting on limiting the progression of these polyps to cancer. Additionally, early detection of small cancers leads to earlier treatment. Overall, earlier detection coupled with prevention via polyp removal should in theory lead to improved survival and decreased colorectal cancer mortality.
Colorectal cancer screening should begin with an assessment of the patient’s risk level based on personal and family medical history. Generally speaking, a personal or family history of colorectal cancer, polyps or certain other disease states, increases the likelihood that an individual may develop polyps or cancer in the future. Patients with such a history may begin screening earlier and undergo more frequent screening thereafter when compared to patients without.
It is important to understand that people with existing gastrointestinal conditions, or with symptoms or signs suggesting the presence of colorectal cancer or polyps, such as rectal bleeding, abdominal pain, a change in bowel habits and unintended weight loss, should also have their colon evaluated.
Types of Colorectal Cancer Screening Tests
There are several common tests used to screen for colorectal cancer:
- Stool test to check for blood or exfoliated DNA in the stool caused by polyps or smaller cancers. Stool tests include the Fecal Occult Blood Test, Fecal Immunochemical Test, and Stool DNA Test. Positive results require colonoscopy.
- Sigmoidoscopy to evaluate the lower third of the colon and rectum using a flexible video scope. Any polyps can be removed. This test is used in conjunction with other tests. Enemas are typically required for preparation.
- Colonoscopy to view the entire colon using a flexible colonoscope, and any polyps found can be removed. Oral bowel preperation is necessary and sedation is customary.
- Double-contrast barium enema to allow a special x-ray of the large intestine, colon, and rectum. Abnormal results require colonoscopy. Oral Bowel preperation is necessary.
- Computerized tomography colonography (CT colonography) to evaluate the bowel, as well as tissue outside the bowel, using a specialized cat scan. Abnormal results require colonoscopy. Oral bowel preperation is necessary.
Factors that can increase the risk of developing colorectal cancer, and thus require more frequent or rigorous screening, include:
- Older age. Though younger adults can develop colorectal cancer, the odds increase greatly after age 50. The majority (9 of 10 people) diagnosed with colorectal cancer are at least 50 years old.
- African-American race. African Americans have a statistically greater risk of developing colorectal cancer than other races.
- Personal history of colorectal cancer or polyps, or of chronic inflammatory bowel disease like ulcerative colitis or Crohn’s disease.
- Family history of colon cancer and colon polyps, with higher risk for those with first-degree relatives (parent, sibling, or child) who developed these conditions before age 60.
- Chronic inflammatory intestinal conditions and diseases of the colon, such as ulcerative colitis and Crohn’s disease.
- Genetic colorectal cancer syndromes, such as familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, also known as Lynch syndrome.
Recommendations for Screening People at Average Risk
Men and women at average risk, who have no personal or family history of cancers, should have colorectal cancer screenings beginning at the age of 50 years. Many healthcare providers recommend that African Americans begin screening at age 45 due to their increased risk. Following are the different types and the recommended frequency for screening tests. Your doctor can tell you which type and frequency is right for you.
- Fecal Occult Blood Testing (FOBT):Yearly, with a follow-up colonoscopy for patients with positive test results on any stool specimen screened.
- Sigmoidoscopy:Every 5 years.
- Combined FOBT and Flexible Sigmoidoscopy: FOBT screening yearly, along with flexible sigmoidoscopy every 5 years.
- Colonoscopy:Every 10 years, with Virtual Colonoscopies recommended every 5 years.
- Double-Contrast Barium Enema (DCBE):Every 5 years.
Recommendations for Screening People at Increased Risk
People with certain risk factors for colon cancer may need to undergo testing earlier than age 50 or have more frequent testing, and screening for these individuals is more likely to be done using colonoscopy.
Family history of colorectal cancer or adenomatous polyps
About 1 in 5 patients with colorectal cancer have some family members who have also been affected by the disease, so more frequent screening is recommended.
- If a person has a first-degree relative (parent, sibling or child) with colon cancer or adenomatous polyps diagnosed before the age of 60 years, or if they have two first-degree relatives diagnosed at any age, screening colonoscopies should begin at the age of 40 (or ten years younger than the earliest family diagnosis) and repeated every 5 years.
- If a person has a first-degree relative with colon cancer or adenomatous polyps diagnosed at the age of 60 or older, or if they have two second-degree relatives (e.g., grandparent or cousin) diagnosed at any age, colorectal cancer screening should be performed beginning at the age of 40 but then as frequently as for persons of average risk.
Familial Adenomatous Polyposis (FAP)
People with genetically-inherited FAP, or who are at risk of having FAP but have not had genetic testing, should have a sigmoidoscopy every year, beginning at 10-12 years old. About 1% of all colorectal cancers are due to FAP.
Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
People with a diagnosis of HNPCC (also called Lynch Syndrome), or who are at increased risk for HNPCC, should have a colonoscopy every 1-2 years beginning at 20-25 years of age, or ten years earlier than the youngest age of colon cancer diagnosis in the family, whichever comes first. HNPCC accounts for 2-4% of all colorectal cancer diagnoses.
Surveillance of People at Increased Risk
If a patient has a history of colorectal cancer, inflammatory bowel disease, or has had adenomatous polyps removed, we recommend ongoing surveillance with more regular colonoscopy screenings.
Personal history of adenomatous polyps removed: A follow-up colonoscopy should be timed depending on the pathology and number of adenomas found.
- Persons who have had numerous, malignant, or large sessile adenoma(s) should have a follow-up colonoscopy within a short period of time, as determined by their doctor.
- Patients who have advanced or multiple tubular adenomas should have their first follow-up colonoscopy after 5 years.
People with a history of colorectal cancer
Patients with a colon or rectal cancer that has been resected with the intention to cure should also have a colonoscopy around the time of the initial diagnosis to rule out synchronous neoplasms.
- If the colon is obstructed prior to the operation, a colonoscopy can be performed approximately 6 months after surgery.
- If the preoperative examination is normal, a subsequent colonoscopy should be performed after 3 years, and then, if normal, every 5 years.
People with inflammatory bowel disease
In patients with chronic, extensive inflammatory bowel disease (e.g., ulcerative colitis or Crohn’s colitis), a surveillance colonoscopy with systematic biopsies is usually recommended.
In general, most patients upon turning 50 should undergo screening. We feel strongly that given the state of current screening modalities, a colonoscopy at least every 10 years represents the most appropriate method for evaluating patients. Newer bowel preparations combined with sedation via anesthesia has made the test easier and safer than ever. For most patients, the test lasts less than 20 minutes and is typically offered as an outpatient procedure. Compared with other approaches, colonoscopy is not only the most effective tool at finding small polyps, but provides the only means to biopsy and remove polyps throughout the entire colon once they are found. This combination has made it the most widely utilized screening test for colorectal cancer and polyps.