Acute Appendicitis as a Harbinger of Colorectal Neoplasms in Patients Aged 40 or Older: A Scoping Review.

[BACKGROUND] Current guidelines on follow-up for acute appendicitis (AA) neglect the risk of colorectal cancer after AA. Heterogeneous and low-level evidence hinders drawing recommendations on follow-up of 40-year-old or older patients after AA, looking for colorectal neoplasms. This study aims to summarize existing research and identify gaps for future studies.

[METHODS] This scoping review was conducted following the 5-stage framework described by Arksey and O'Malley, and is based on the JBI (Joanna Briggs Institute) guidelines. The searching process followed the Cochrane Handbook and the Cochrane Methodological Expectations of Cochrane Intervention Reviews (MECIR) for conducting the search and the PRISMA 2020 for reporting. Protocol registration on Open Science Framework.

[RESULTS] Seventeen of 3778 studies met the inclusion criteria, all retrospective: 4 population-based and 13 cohort studies. Half focused on patients 40 years of age or older, while others analyzed older patients or performed a subanalysis by age. Seven studies had a 36-month follow-up, 2 had 24 months, and one had 12 months. Remaining studies provided subclassifications. The rate of colorectal neoplasms found at follow-up ranged from 0.5% to 34.6%, while the increased risk varied from 1.2 to 38.5 times, reflecting marked heterogeneity in study design and follow-up modality. Neoplasms were detected in all colorectal regions. Thirteen studies supported follow-up after AA, 3 expressed conditional favor, and one opposed it.

[CONCLUSIONS] Many retrospective studies suggest an increased risk of colorectal neoplasms in AA patients aged 40 years or older. However, current evidence does not support solid recommendations for standard follow-up. This scoping review highlighted a gap in the literature, and a prospective study framework has been outlined to improve evidence quality on this topic.