Week 3: Screening and surveillance for colon cancer

Question 1

recommended screening by US preventive services task force for colorectal cancer

Answer 1

• Age 50-75 Screen with high sensitivity FOBT, sigmoidoscopy, or colonoscopy
• Age 75-85: do not screen routinely

Question 2

fecal immunochemical test (FIT)

Answer 2

• high NPV for colon cancer
• loses PPV when digital collection.
• but doesn’t pick up advanced neoplasms (>1 cm, villous, or high grade dysplasia)
• stool DNA is more sensitive but less specific than FIT

Question 3

Frequency of screening

Answer 3

• sigmoidoscopy every 5 years or less frequently
• stool hemoocults or immunochemical tests yearly
• colonoscopy every 10 years
• if 1-2 small tubular adenomas found, screen again in 5-10 years

Question 4

Screening in those with inflammatory bowel disease

Answer 4

• UC and Crohn’s are associated with increase risk of colon cancer
• they should be screened with colonoscopy 8-10 years after having disease
• Crohns: larger increased risk of cancer in small bowel

Question 5

Right colon screening failure

Answer 5

• high mortality if cancer in right colon
• half of advanced neoplasms in proximal colon had no adenomas distal to splenic flexure
• some doctors don’t go to cecum or too rapid inspection