Lynch syndrome (LS) is the most common of hereditary cancer syndromes. In Finland, carriers of the mutation number around 10,000 individuals, while in all of Europe the number is several million. These individuals are healthy carriers of a mutation that turns off a repair gene dedicated to fixing DNA damage, resulting very likely in the onset of cancer.
Colorectal cancer is the most common cancer in carriers of Lynch syndrome. Preventative measures have included regular colonoscopies and the removal of adenomatous polyps, which have been considered as the precancerous lesion also in LS.
The study, published in the latest issue of the Gastroenterology journal, compared colonoscopies performed in Finland, the Netherlands and Germany. In Finland, the surveillance interval for Lynch syndrome carriers has long been two to three years, while in the Netherlands the interval has been one to two years. Germans have undergone annual colonoscopies. Recommendations vary between one- and two-year intervals.
No significant differences in the incidence or stage of colorectal cancer were found between the various surveillance strategies. The data was collected from 16,327 colonoscopies performed on 2,747 patients.
“Our results casts the recommended interval of one or two years in uncertain light, since no benefit was gained from annual colonoscopies,” says Toni Seppälä, one of the principal authors of the article, representing the University of Helsinki and the Helsinki University Central Hospital.
According to the study, the following factors increased colorectal cancer risk: prior colorectal cancer diagnosis, male gender, age of 40 years of more, prior detection of an adenoma and the presence of MLH1/MSH2 gene mutations.
“Further studies should examine whether shorter surveillance intervals adapted to risk factors offer any benefit. The focus should also be directed at cancer biology: why don’t shorter surveillance intervals and the removal of precancerous lesions decrease the incidence of cancer? Do adenomas actually develop into cancer even faster than thought, or is it not even possible to detect precursor lesions in colonoscopy?”
In Finland, families carrying Lynch syndrome have been systematically mapped and monitored already for 35 years.
“The belief in the international LS research community was that colorectal cancer is more prevalent in Finnish LS patients. This notion has now been proven false,” says Jukka-Pekka Mecklin, a research professor at the University of Jyväskylä and the founder of Finland’s LS register.
“We must ensure that every individual with the inherited gene defect remains under surveillance. Therefore, the surveillance should not place an unreasonable burden on the participants.”
Christoph Engel, M.D., Hans F. Vasen, M.D., Toni Seppälä, M.D. et al. No Difference in Colorectal Cancer Incidence or Stage at Detection by Colonoscopy Among 3 Countries With Different Lynch Syndrome Surveillance Policies, Gastroenterology 2018 DOI: https://doi.org/10.1053/j.gastro.2018.07.030
Toni Seppälä, University of Helsinki and Helsinki University Central Hospital, firstname.lastname@example.org, tel. +358 44 339 8858
Jukka-Pekka Mecklin, University of Jyväskylä, email@example.com, tel. +358 50 361 5920