DIFFERENCES IN THE DISTRIBUTION OF HISTOLOGY OF COLORECTAL ADENOMAS BETWEEN INDIVIDUALS UNDER AND OVER THE AGE OF 50

Aims While the incidence of Colorectal cancer(CRC) is decreasing among individuals over 50 years it is increasing within younger adults. A study by Reinier et al showed that CRC among young adults is now diagnosed at a later stage compared to 1990, indicating that the increasing incidences are not an effect of a shift in age at diagnosis. However, it is still unknown if there are differences among precursor adenomas between adults < 50 years compared to those above.

Methods 336582 screening colonoscopies between 2007 and 2019 were assessed within the Austrian quality-assurance program. Main reason for undergoing colonoscopy of asymptomatic individuals under the age of 50 was fear of cancer. The proportion of different types of adenomas between patients aged < 50 and ³50 was compared within this study.

Results 336.582 screening colonoscopies were analyzed. 12.256(3,6%) of patients were under the age of 50 and 324.326(96,4%) above. Adenomas were detected in 12,5% (n=1.531) within individuals < 50years and in 23,7%(n=76.742) within above. 9,5% (n=146) of adenomas among adults under 50 years were sessile-serrated-polyps(SSP) compared to 6,5% (n=4951) among those older than 50 (p< 0,001). 2,9% (n=45) were tradional-serrated-polyps(TSA) in the age group < 50 compared to 1,2% (896) in age group ³50 (p< 0,001). Proportion of tubulaer adenomas was 71,1% (n=1089) within individuals < 50 years and 76,2% (n=58.480) within patients older than 50 years (p< 0,001). 15,5% (n=238) vs. 15,3% (11.766) of adenomas were tubulovilloes (p=0,81) and 0,8% (n=13) vs. 0,8% (n=639) were villoes adenomas (p=0,89) comparing < 50 and ³50 year-old individuals (p=0,81).

Conclusions Individuals younger than 50 years had significant higher proportions of SSAs, as well as TSAs, compared to individuals older than 50. In contrast the proportion of tubular adenomas was significant lower among 20-49 year old patients. There was no difference in proportion of tubulovilloes and villoes adenomas.