2.1. Study design and participants

This is a retrospective observational study involving a sample of patients diagnosed with rectal cancer in Saudi Arabia, Jeddah. The inclusion criteria were a diagnosis of rectal cancer of any stage from 2017 to 2020, a flexible endoscopy report, an MRI report, age >18 years, and rectal cancer height ≤18 cm from the anal verge. The exclusion criterion was sigmoid cancer height >18 cm. This study primarily aimed to compare between flexible endoscopy and MRI in the diagnosis of rectal cancer by measuring tumor height. The tumor height was measured from the anal verge to the distal part of the tumor. Agreement between the measurements was tested using intraclass correlation coefficient (ICC), and ICC values ≥0.75 were considered as excellent agreement, 0.4–0.75 as fair to good agreement, and <0.4 as poor agreement.