From the Guidelines
After a colonoscopy, you should not do an iFOBT yearly, but instead follow your doctor's recommended screening schedule based on your colonoscopy findings. For most people with normal results and average risk, the next colonoscopy would be needed in 7-10 years, not annual iFOBT testing 1. If your colonoscopy showed polyps or other abnormalities, your doctor will provide a specific follow-up schedule, which might be a repeat colonoscopy in 3-5 years depending on the findings, rather than iFOBT testing.
Key Considerations
- The USMSTF/ACS panel recommends against the routine use of fecal occult blood testing of post-polypectomy patients 1.
- iFOBT is primarily used as an initial screening tool or for people who cannot or choose not to undergo colonoscopy.
- Colonoscopy is considered more thorough than iFOBT since it directly visualizes the entire colon and can remove precancerous polyps during the procedure.
Follow-Up Schedule
- Patients with one or two small (less than 1 cm) tubular adenomas should have their next follow-up colonoscopy in five to 10 years 1.
- Patients with three to 10 adenomas, any adenoma 1 cm or larger, or any adenoma with villous features or high-grade dysplasia should have their next colonoscopy in three years 1.
- Patients undergoing curative resection for colon or rectal cancer should undergo a colonoscopy one year after the resection 1. If you have ongoing symptoms like rectal bleeding, abdominal pain, or changes in bowel habits after a colonoscopy, contact your doctor promptly rather than waiting for your next scheduled screening.
From the Research
Screening Intervals for Colonoscopy
- The recommended screening interval for colonoscopy varies depending on the individual's risk level, with average-risk individuals typically recommended to undergo screening every 10 years 2, 3.
- For high-risk individuals, such as those with a positive family history of colorectal cancer or advanced colorectal polyp, screening is recommended to begin at age 40, with intervals of every 5-10 years 2.
- A study found that the yield of a second screening colonoscopy 10 years after an initial negative examination in average-risk individuals was significant, with 59.3% of patients having at least one polyp, including 38.1% with at least one conventional adenoma 3.
Relationship Between Screening Interval and Cancer Risk
- Having at least one colonoscopy within the previous 10 years has been associated with a reduced risk of colorectal cancer mortality, with a 51% reduced hazard of colorectal cancer death 4.
- The protective benefit of colonoscopy may be maintained well beyond 74 years, a common upper age limit recommended by screening guidelines 4.
- However, the risk reduction related to colonoscopy may be lower for proximal cancers 4.
Current Screening Guidelines
- Current guidelines recommend screening colonoscopy at 10-year intervals in average-risk individuals who had baseline screening colonoscopy with no polyps or only hyperplastic polyps ≤5 mm in the recto-sigmoid colon 3.
- The American College of Gastroenterology and the U.S. Multi-Society Task Force on Colorectal Cancer recommend screening for colorectal cancer in average-risk individuals starting at age 50, with options including colonoscopy every 10 years, annual fecal immunochemical testing, or stool DNA testing every 3 years 5.
Fecal Occult Blood Test (FOBT) and Colonoscopy
- A positive fecal occult blood test is an indication for colonoscopy, and individuals with positive FOBT results, especially those with high quantitative test results, should be encouraged to have a colonoscopy due to the high probability of adenomatous polyps and colorectal cancer 6.