The interval at which an individual undergoes a repeat colonoscopy because of previous pre-cancerous polyps, a practice known as surveillance should be tailored to the individual and not simply be determined by the results of prior colonoscopies, according to Regenstrief Institute research scientist Thomas F. Imperiale, M.D.

In an editorial in the American Journal of Gastroenterology, he calls for "precision surveillance," a phrase he has coined to echo the personalized, targeted focus of precision medicine and the application of these concepts to colon cancer screening and surveillance.

Precancerous polyps

"The goal of colorectal cancer surveillance is to reduce incidence and death from colorectal cancer," said Dr. Imperiale. "The only factor we currently consider for whether and when to do a surveillance colonoscopy is the number and size of precancerous polyps found on a previous colonoscopy screening. No other factors are considered; this practice does not always make good clinical sense.

"Precision surveillance goes beyond that one element (what is in the colon) and considers the patient's phenotype – personal characters such as age, personal medical history, BMI (body mass index), and health habits such as smoking," said Dr. Imperiale.

"And when the data become more widely available, consideration of when to rescope should include the skill of the colonoscopists who performed the previous colonoscopies," said Dr. Imperiale.

Dr. Imperiale says that his editorial, "Thinking Big About Small Adenomas: Moving Towards 'Precision Surveillance'" is a small step toward advancing surveillance colonoscopy by expanding the proportion of persons considered "low-risk" from one or two small, precancerous polyps to up to four such polyps.

The giant leap, he says, would be to employ precision surveillance and make screening recommendations truly personalized and based on the patient, their polyps, and their colonoscopist. Although studies suggest that the smaller the precancerous lesions are, the longer it takes for them to become cancerous, scientists do not have an accurate picture of the natural history of these lesions because they are removed upon discovery. It is known that most do not become cancerous.

"While we want to keep an eye on those individuals who have shown they can grow precancerous polyps, we need to balance being appropriately aggressive in those with whom we should be, with backing off from intense treatment for people who do not require it," said Dr. Imperiale. "Precision surveillance starts to get at that issue."