Screening of GI Neoplasia Flashcards
Most screening is done for colorectal cancer (CRC).
Just know this.
Define colorectal cancer
Adenocarcinoma of colon or rectum
How i the incidence of CRC changing in North America
Decreasing incidence in >50yo
Increasing incidence in <50yo
Describe the adenocarcinoma sequence of CRC
How long does it take for the progression from adenoma to adenocarcinoma?
10 years
Define adenoma
Benign epithelial tumour in which cells are derived from glandular tissue
Define advanced adenoma
Adenoma >1cm
…?
Risk factors for CRC
- FAMILY HISTORY (much greater risk in patients with one or more first-degree relative with advanced adenoma or CRC)
- Older age increases risk
- Ethnicity (highest incidence in Black and Native Americans)
- Obesity and lack of physical activity (esp. weight gain in early adulthood)
- Diet (red meat)
- Smoking and alcohol
- Aspirin (ASA) - decreases risk
How does bariatric surgery affect the risk of CRC
Decreases risk
Name 3 diseases that can increase the risk of CRC
Inflammatory bowel disease
Hereditary CRC syndromes
Previous abdominal or pelvic radiation
What is the goal of CRC screening?
To diagnose and remove adenomas (as polyps) before they develop into CRC (this decreases incidence and mortality from CRC)
What type of patients qualify for CRC screening?
Person with NO symptoms AND NO personal or family history of adenomatous polyps or CRC.
Average-risk screening
Average risk screening is defined as occurring in asymptomatic patients with none of the following:
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High-risk screening
Occurring in asymptomatic patients with one or more of the following:
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2 types of screening modalities
- stool-based
- direct visualization-based
3 stool-based screening modalities
- Fecal occult blood test (FOBT)
- Fecal immunochemical test (FIT)
- Multitarget stool DNA
Describe fecal occult blood test
Describe the FIT test
This test directly measures hemoglobin in stool. Requires 1 sample.
Describe multi-target stool DNA test
This test is an assay for common adenocarcinoma molecular markers. It is usually done in conjunction with FIT.
Requires a whole stool sample.
Note: If any of the stool based tests are positive, you need to go for a visualization based test (i.e. colonoscopy) as well to visualize the tumour/lesion and remove it.
Advantages of stool-based screening modalities
Can be done at home
Disadvantages of stool-based screening modalities
?
Name 3 direct-visualization screening modalities
- Colonoscopy
- Flexible sigmoidoscopy
- CT colonography
Compare the advantages/disatvantages/risks of direct visualization screening modalities
NOTE: we do not really do flexible sigmoidoscopy anymore
