POST-COLONOSCOPY COLORECTAL CANCER IN LYNCH SYNDROME IS ASSOCIATED WITH QUALITY ISSUES DURING SURVEILLANCE

Aims To assess the effect of quality endoscopic factors on the development of PCCRC during surveillance in LS mutation carriers.

Methods Multicenter study with 25 high-risk CRC clinics from Spain and 1 from The Netherlands. Demographic, genetics, cancer history, and surveillance protocols from patients LS carriers of verified pathogenic mutations(n=1,746) have been prospectively collected between 2015- 2019. For the current analysis, we focused on healthy-carriers(HC) defined as carriers without CRC prior or in the index colonoscopy. To assess the effect of colonoscopy on PCCRC incidence we evaluated the report of every surveillance colonoscopy(n=3,284). We compared colonoscopies previous to PCCRC with colonoscopies of carriers without cancer. Quality colonoscopy parameters(completeness, bowel-preparation, scope definition and enhancement techniques), time-intervals and findings from a previous colonoscopy were analyzed. Multivariate logistic-regression was performed to identify CRC risk factors.

Results We included 893 HC, 596(63.7%) female, with a median age of 50.5±14.8 years, a median colonoscopy follow-up of 6.3±4.2 years and 4.8±2.7 colonoscopies. The distribution per gene was: 285(31.9%)MLH1, 316(35.4%)MSH2, 212(23.7%) MSH6 and 80(9%) PMS2 carriers. During surveillance 48(5.4%) PCCRC were diagnosed [17(35.4%) MLH1, 24(50%) MSH2, 6(12.5%) MSH6 and 1(2.1%)PMS2]. The mean age at diagnosis was 51.1±10.6 years, the mean follow-up 5.8±5.5 years, 32(66.7%). When analyzing quality colonoscopy indicators, a previous incomplete colonoscopy and previous colonoscopy performed with standard definition appeared as independent risk factors of PCCRC [OR=6.7(95%CI 1.4-33);p0.018 and OR=5.9(95%CI 1.41-25); p0.015]. Besides, an interval between colonoscopies of more than 36 months, or an advanced adenoma in the previous colonoscopy increased more than 4 times the risk of PCCRC[OR=4.1 (95%IC 1.7-9.8);p0.002 and OR=4.16 (95%CI 1.6-10.6);p0.003].

Conclusions PCCCR incidence is associated with quality issues in LS carriers under surveillance colonoscopy. High quality colonoscopy and appropriate interval (< 36 months) should be strongly advised. Patients with an advanced adenoma may benefit of shorter interval between colonoscopies.