Screening colonoscopy is thought to be a powerful and cost-effective tool to reduce colorectal cancer incidence and mortality.
Whether and when colonoscopy with negative findings has to be repeated is not well defined.
Professor Herman Brenner and colleagues from Germany assessed the long term risk of clinically manifest colorectal cancer with negative findings at colonoscopy.
The research team included 380 cases and 485 controls in a population based case-control study.
The team used detailed history, and obtained results of previous colonoscopies by interview and from medical records.
|Patients may not need repeat colonoscopy for 20 years or more|
Adjusted relative risks of colorectal cancer with a previous negative colonoscopy vs those without previous colonoscopy were estimated.
The researchers found that subjects with previous negative colonoscopy had a 74% lower risk of colorectal cancer than those without previous colonoscopy.
The team observed this low risk even if the colonoscopy had been done up to 20 or more years previously.
Low risks were seen particularly for sigma cancer, and for rectal cancer.
The researchers noted that the risk was lower after a negative screening colonoscopy at ages 55 to 64 and older.
Professor Brenner's team concluded, “Subjects with negative findings at colonoscopy are at very low risk of colorectal cancer.”
“The patients might not need to undergo repeat colonoscopy for 20 years or more, if at all.”
“The possibility of extending screening intervals to 20 years or more might reduce complications and increase the feasibility and cost-effectiveness of colonoscopy based screening programs.”