COLON CANCER SCREENING METHODS

OTHER:
















Test Description/Accuracy Recommendations/Cost
Colonoscopy DESCRIPTION
  • Procedure where an endoscope is inserted through the anus and advanced all the way to the terminal ileum
  • Endoscope allows visualization of the entire colon and a portion of the terminal ileum

  • Advantages: allows visualization of the entire colon; considered the "gold standard" for colon cancer screening/detection; allows for biopsy of lesions and removal of polyps; if normal, screening interval is 10 years
  • Disadvantages: invasive procedure that requires sedation; bowel prep is required that may be uncomfortable; serious adverse events (e.g. bleeding, perforation) occur in about 0.28% of procedures [4]

ACCURACY
  • Colonoscopy is considered the reference standard
  • It is estimated that the colorectal cancer miss rate for colonoscopy is as high as 6%. The miss rate for adenomas > 1 cm is 12 - 17%. [4]
RECOMMENDATIONS
  • USPSTF - screen everyone every 10 years from age 50 - 75. After age 75, screening should be individualized.
  • ACS - screen everyone every 10 years starting at age 50
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. Screen every 10 years. The ACG states that colonoscopy is the preferred method.
  • ACP - screen everyone every 10 years from age 50 - 75

COST
  • ∼ $500
  • Cost is higher if biopsies are performed
Flexible sigmoidoscopy (Flex sig) DESCRIPTION
  • Procedure where an endoscope is inserted through the anus and advanced into the sigmoid colon. The standard sigmoidoscope is 60 cm long.
  • Approximately two-thirds of colorectal cancers and adenomas are located in the rectum and sigmoid colon [7]

  • Advantages: performed in office without sedation; prep only requires 2 fleet enemas although oral prep may be better; allows for biopsy and polypectomy
  • Disadvantages: only allows visualization of the sigmoid and descending colon; patient discomfort; perforation and bleeding are rare but may occur [6]

ACCURACY
  • No well-done studies have compared flexible sigmoidoscopy to colonoscopy in average-risk populations
RECOMMENDATIONS
  • USPSTF
    • Flex sig alone - screen everyone every 5 years from age 50 - 75. After age 75, screening should be individualized.
    • Flex sig + FIT - screen everyone with flex sig every 10 years + yearly FIT from age 50 - 75. After age 75, screening should be individualized.
  • ACS - screen everyone every 5 years starting at age 50
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. Screen every 5 - 10 years.
  • ACP
    • Flex sig alone - screen everyone every 5 years from age 50 - 75
    • Flex sig + FIT or gFOBT - screen everyone with flex sig every 5 years + FIT or gFOBT every 3 years from age 50 - 75
  • CTFPHC - screen everyone with flex sig every 10 years + FIT or gFOBT every 2 years from age 50 - 74

COST
  • ∼ $200
  • Cost is higher if biopsies are performed
CT Colonography DESCRIPTION
  • Specialized CT scan of the abdomen that creates 2D and 3D images of the colon for polyp and neoplasm detection
  • Patient must undergo bowel prep beforehand. A small amount of contrast may be mixed with the prep so that residual fluid and stool is "tagged." This helps distinguish the residua from soft tissue masses.
  • During the scan, a rectal tube is inserted so that the colon can be insufflated with CO2 or room air
  • Patients with polyps ≥ 6 mm are referred for colonoscopy [6]

  • Advantages: no sedation is required; procedure takes about 10 minutes with no recovery time; colon perforation is rare; in studies, significant extracolonic findings are found in 4.5% of patients
  • Disadvantages: bowel prep is recommended; colonoscopy may be necessary depending on findings; patient receives small amount of radiation; extracolonic findings may lead to unnecessary testing [6]

ACCURACY
  • Sensitivity (colorectal cancer): 96%
  • Sensitivity (adenomas ≥ 10 mm): 85 - 93%
  • Specificity (adenomas ≥ 10 mm): 97%
  • Sensitivity (adenomas 6 - 9 mm): 70 - 86%
  • Specificity (adenomas 6 - 9 mm): 86 - 93% [6]
RECOMMENDATIONS
  • USPSTF - screen everyone every 5 years from age 50 - 75. After age 75, screening should be individualized.
  • ACS - screen everyone every 5 years starting at age 50
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. Screen every 5 years.

COST
  • ∼ $600
  • Reimbursement for screening varies
Double-contrast barium enema

(air-contrast barium enema)
DESCRIPTION
  • Procedure where a tube is inserted into the rectum and barium is infused. The patient's position is adjusted under fluoroscopy so that the barium coats the entire lining of the colon. After removing some barium, the colon is then insufflated with air. Air and barium serve as the "double-contrast," and radiographic images are obtained.
  • Colon prep before the procedure is required. The procedure typically lasts 20 - 40 minutes. [6]

  • Advantages: no sedation is required; no recovery time
  • Disadvantages: bowel prep is required; colonoscopy may be necessary depending on findings; exam can be uncomfortable; test accuracy highly dependent on examiner's experience

ACCURACY
  • Sensitivity (colorectal cancer): 85 - 97%
  • Sensitivity (adenomas > 7 mm): 73% (based on 1 study, n=56) [6]
RECOMMENDATIONS
  • ACS - screen everyone every 5 years starting at age 50

COST
  • ∼ $250
Guaiac-based fecal occult blood test
(gFOBT)

(Hemoccult®)
DESCRIPTION
  • Guaiac-based fecal occult blood tests detect blood in the stool through the pseudoperoxidase activity of hemoglobin
  • Patients typically collect 1 stool sample on 3 different days at home. The samples are developed in a doctor's office or lab.
  • NSAIDs should be avoided for 7 days before and during the collection period
  • Vitamin C in excess of 250 mg/day should be avoided for 3 days before and during the collection period (may cause false-negative)
  • Red meats should be avoided for 3 days before and during the collection period
  • Specimens should be developed within 14 days of collection
  • Hemoccult SENSA is more sensitive than Hemoccult II [5,6]

  • Advantages: performed at home; no procedure; inexpensive
  • Disadvantages: diet and drug restrictions; positive result requires colonoscopy; more frequent testing; does not detect polyps; low sensitivity

ACCURACY
Hemoccult II
  • Sensitivity (colorectal cancer): 13%
  • Sensitivity (advanced adenoma): 11%
  • Specificity (combined): 95% [8]
Hemoccult SENSA
  • Sensitivity (colorectal cancer): 64%
  • Specificity (colorectal cancer): 90%
  • Sensitivity (advanced adenoma): 41%
  • Specificity (advanced adenoma): 91% [9]
  • NOTE: In this study (n=5799), the reference standard was flex sig or colonoscopy
RECOMMENDATIONS
  • USPSTF - screen everyone annually from age 50 - 75. After age 75, screening should be individualized.
  • ACS - screen everyone annually starting at age 50. Hemoccult SENSA is preferred.
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. Screen annually. Only Hemoccult SENSA should be used. FIT is preferred over gFOBT.
  • ACP - screen everyone aged 50 - 75 annually
  • CTFPHC - screen everyone with flex sig every 10 years + FIT or gFOBT every 2 years from age 50 - 74

COST
  • Hemoccult SENSA - ∼ $6
  • Hemoccult II - ∼ $3
Fecal immunochemical test

(FIT)
DESCRIPTION
  • Like gFOBT, FIT is performed on a stool sample collected by the patient
  • FIT testing detects human globin, a component of human hemoglobin. FIT differs from gFOBT in that it directly detects blood in the stool where gFOBT relies on the peroxidase activity of hemoglobin.
  • Diet, medications, and supplements do not interfere with FIT testing. FIT testing is also more specific for lower GI bleeding because globulin is degraded by digestive enzymes in the upper GI tract.
  • Examples of currently available FIT tests include Hemoccult ICT, OC-Light, Hemosure, QuickVue iFOB, and Clearview. Some tests use cards and some tests use bottles. The optimal number of samples to test has not been determined but varies from one to three. The US Multi-Society Task Force on colorectal cancer recommends testing one sample.
  • Most tests give only qualitative result (positive or negative) while a few tests give qualitative and quantitative results (i-Chroma iFOBT, OC-Micro, OC-Sensor) [5,6,14]

  • Advantages: performed at home; no procedure; inexpensive; no diet or medication restrictions
  • Disadvantages: positive result requires colonoscopy; more frequent testing; does not detect polyps

ACCURACY
Hemoccult ICT
  • Sensitivity (colorectal cancer): 82%
  • Specificity (colorectal cancer): 97%
  • Sensitivity (advanced adenoma): 30%
  • Specificity (advanced adenoma): 97% [9]
  • NOTE: In this study (n=5356), the reference standard was flex sig or colonoscopy, and three stool samples were tested
OC FIT-CHEK
  • Sensitivity (colorectal cancer): 74%
  • Sensitivity (advanced adenoma): 24%
  • Specificity (negative colonoscopy): 96% [10]
  • NOTE: In this study (n=9989), only one stool sample was tested
RECOMMENDATIONS
  • USPSTF
    • FIT alone - screen everyone annually from age 50 - 75. After age 75, screening should be individualized.
    • FIT + Flex Sig - screen everyone with flex sig every 10 years + yearly FIT from age 50 - 75. After age 75, screening should be individualized.
    • FIT + fecal DNA - screen everyone every one or three years from age 50 - 75. After age 75, screening should be individualized.
  • ACS - screen everyone annually starting at age 50
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. Screen annually. FIT is preferred over gFOBT.
  • ACP
    • FIT alone - screen everyone age 50 - 75 annually
    • Flex sig + FIT or gFOBT - screen everyone with flex sig every 5 years + FIT or gFOBT every 3 years from age 50 - 75
  • CTFPHC - screen everyone with flex sig every 10 years + FIT or gFOBT every 2 years from age 50 - 74

COST
  • Hemoccult ICT - ∼ $3
  • Hemosure - ∼ $5
  • OC-Light - ∼ $3
Fecal DNA test

(Cologuard®)
DESCRIPTION
  • Fecal DNA tests are performed on a single sample of stool that is collected by the patient at home
  • Colorectal cancers and adenomas continually shed cells into the stool. These cells contain certain types of genetic mutations that are common in many cancerous and precancerous tumors. Fecal DNA tests are able to detect these mutations in cells present in the stool sample.
  • The test is not 100% sensitive in that not all cancers or precancerous lesions carry the genetic mutations that are detected.
  • The test is marketed under the name Cologuard®. A FIT test is also performed with the Cologuard test. [5,6,10]

  • Advantages: performed at home; no procedure; no diet or medication restrictions
  • Disadvantages: positive result requires colonoscopy; expensive; does not detect polyps; does not detect all cancers; optimal screening interval has not been determined; unclear how to handle a positive test that is followed by a negative colonoscopy

ACCURACY
Cologuard
  • Sensitivity (colorectal cancer): 92%
  • Sensitivity (advanced adenoma): 42%
  • Specificity (negative colonoscopy): 90% [10]
RECOMMENDATIONS
  • USPSTF - screen everyone every one or three years from age 50 - 75. After age 75, screening should be individualized.
  • ACS - may be used for screening patients starting at age 50 years. Optimal screening interval is uncertain.
  • ACG - start screening African Americans at age 45. Screen everyone else at age 50. The optimal screening interval is unknown, but screening at intervals < 3 years would be cost prohibitive.

COST
  • Cologuard - ∼ $600
mSEPT9 DNA testing

(Epi proColon®)
DESCRIPTION
  • mSEPT9 DNA testing is performed on a blood sample
  • The test detects methylated SEPT9 DNA, which in high quantities, is a marker for colorectal cancer
  • The test is marketed under the name Epi proColon® [11]

  • Advantages: blood test; no procedure
  • Disadvantages: low sensitivity; positive result requires colonoscopy; does not detect polyps

ACCURACY
Epi proColon
  • Sensitivity (colorectal cancer): 48%
  • Sensitivity (advanced adenoma): 11%
  • Specificity (colorectal cancer): 92% [11]
RECOMMENDATIONS
  • No organization currently recommends this test

COST
  • Epi proColon - ∼ $91