Best colonoscopy frequency in Lynch syndrome unclear

Last Updated: 2018-08-13

By David Douglas

NEW YORK (Reuters Health) - In patients with Lynch syndrome, annual colonoscopy is no more effective in detection of colorectal cancer (CRC) than is surveillance every two to three years, according to European researchers.

"Contrary to our expectation," Dr. Christoph Engel told Reuters Health by email, "our study did not show an advantage of strict annual colonoscopies regarding lower cancer incidence or more favorable tumor stages."

In a July 26 online paper in Gastroenterology, Dr. Engel of the University of Leipzig, Germany, and colleagues note that patients with Lynch syndrome are at elevated risk of developing CRC. But there is no international consensus on the appropriate interval for colonoscopic surveillance, they add.

To investigate, the researchers examined data on more than 16,000 colonoscopic examinations conducted between 1984 and 2014 in 2,747 patients with Lynch syndrome. These came from Germany, which recommends annual colonoscopy, from the Netherlands, which advises colonoscopy at one to two years, and from Finland, in which the interval is two to three years.

Among inclusion criteria were a proven pathogenic germline mutation in either the MLH1, MSH2 or MSH6 gene, and having completed at least two surveillance colonoscopies after registry entry. Patients with PMS2 (or EPCAM) mutations were not included due to low sample size.

The team then went on to perform multivariable Cox regression analyses to identify risk factors such as diagnosis of CRC before the index colonoscopy, sex, age and adenoma at the index colonoscopy. The prevalence of adenomas at the index colonoscopy was 10.2%, while CRC prevalence was 2.3%.

The median per-patient observation time was 7.8 years and patients had a median of five consecutive colonoscopies. "Observed colonoscopy intervals were largely in accordance with the country-specific recommendations," the researchers note.

Patients in the lowest-risk group (one or no risk factors) had a 10-year CRC risk of 4.1%. For those in the highest-risk group (four or five risk factors) the corresponding risk was 18.4%, a significant difference.

Although risk factors clearly had an impact, the team did not find a significant reduction in CRC incidence or stage of detection across countries and their respective surveillance intervals.

"The clinical implication is that an interval of two years might be sufficient and only patients predicted to have a high CRC risk based on individual risk factors may benefit from shorter intervals," said Dr. Engel. "However, further research and clinical studies are needed to define risk-adapted surveillance programs and to confirm whether they are safe and effective."

Dr. P l M ller, who heads the research group on inherited cancer at Oslo University Hospital, in Norway, told Reuters Health by email, "In sum these findings should question the rationale for colonoscopy more frequent than every three years, not only so for economic and resource-allocation reasons but with respect to side effects of colonoscopy as well."

However, added Dr. M ller, who was not involved in the new work, "The validity of grouping carriers of pathogenic variants of the four genes together as Lynch Syndrome is increasingly questionable, which should have been discussed in more detail."

SOURCE: https://bit.ly/2P4iE8A

Gastroenterology 2018.