Surveillance no bar to colorectal cancer in Lynch syndrome

Last Updated: 2015-12-23

By David Douglas

NEW YORK (Reuters Health) - Despite colonoscopic surveillance, colorectal cancer is frequent in patients with Lynch syndrome, but deaths are few, according to a multinational study.

As Dr. Pal Moller told Reuters Health by email, "In contrast to current belief, colorectal cancer was in general not prevented by colonoscopies with removal of adenomas, which indicated that inherited colon cancer may not always be preceded by a visible noninvasive precursor lesion -- while the colon cancer seems to have a long time window in which it may be detected, removed, and cured."

Dr. Moller added, "Leading centers in Europe and Australia have joined forces to produce the first comprehensive report on prospectively observed effects of interventions to prevent and cure inherited colorectal and gynecological cancer. In former generations the cancers were in general lethal."

In a December 9 online paper in Gut, Dr. Moller, of the Norwegian Radium Hospital, Oslo, and colleagues note that they followed 1942 patients without previous cancer carrying Lynch syndrome-associated mutations affecting MLH1, MSH2, MSH6 or PMS2.

Over more than 13,700 observation years of follow-up, 314 subjects developed cancer. This was colorectal in 151, endometrial in 72, and ovarian in 19. Cancers were detected from 25 years onward in MLH1 and MSH2 mutation carriers, and from about 40 years in MSH6 and PMS2 carriers.

As to the first cancer detected in each patient, the colorectal cancer cumulative incidence at 70 years was 46% for carriers of MLH1, 35% for MSH2, 20% for MSH6 and 10% for PMS2.

The corresponding cumulative incidences for endometrial cancer were 34%, 51%, 49% and 24%. For ovarian cancer they were 11%, 15%, 0% and 0%.

Ten-year crude survival was 87% after any cancer. Such survival was 91% if the first cancer was colorectal, 98% if endometrial and 89% if ovarian.

"These observations," continued Dr. Moller, "are important for tailoring health service to this high-risk group for cancers, and the collaborative group is preparing more reports to describe the success of our interventions in more detail."

"Genetic testing is now cheap," he added, and "genetic testing to identify those at risk should be made available to all who want to know, so that they may benefit."

In fact, Dr. Moller said these data he and his colleagues developed are on a website with an online calculator "where any carrier of the genetic variants causing Lynch syndrome may see their risk." (This is accessible via http://lscarisk.org/.)

Commenting on the findings by email, Dr. Christophe Cellier told Reuters Health that the "risk of cancer may be different depending on the identified mutation and thus surveillance may be adapted." However, Dr. Cellier of Hospital European Georges-Pompidou, Paris, went on to point out that the paper does not assess quality factors associated with colonoscopy.

"Indeed," he continued, "in our French surveillance network program supported by the French National Cancer Institute, we have suggested that an optimal colonoscopy surveillance with quality indicators (good colonic preparation, chromoendoscopy with indigo carmine) together with strict interval colonoscopic surveillance (one or two years depending of the presence or absence of adenomas in the colon) was associated with an increase polyp detection rate and a significant decrease of interval colorectal cancer in Lynch patients."

A number of organizations supported this research. One coauthor reported a patent pending.

SOURCE: http://bit.ly/1Mwepsn

Gut 2015.