Incidental findings on staging CT for rectal cancer: Frequency, clinical significance and outcomes

To assess the prevalence, clinical significance, and outcomes of incidental findings in CT studies performed for rectal cancer staging.

This retrospective study was performed at a tertiary colorectal imaging institution. Institutional review board approval was obtained. Consecutive patients who had a CT of the chest, abdomen and pelvis for rectal cancer staging between March 2014 and March 2021 were identified. Patients with a pathologically confirmed primary rectal cancer were included. The imaging reports were reviewed for incidental findings (IFs), which were classified into high, moderate, and low categories, according to their clinical significance. Medical records were reviewed to assess the clinical outcomes of the highly significant IFs.

There were 241 eligible patients with a mean age of 67 years (92 females). A total of 942 IFs were found in 235 patients (97.5 %). There were 91 IFs (10 %) of high clinical significance, 371 (39 %) of moderate clinical significance, and 480 (51 %) of low clinical significance. There were 8 synchronous malignancies, all of which were highly clinically significant IFs. There were 4 lung adenocarcinomas, 1 bladder urothelial carcinoma, and 3 renal cell carcinomas. Six patients did not have any IFs (2.5 %).

IFs were seen in 97.5 % of staging CT scans for rectal cancer, 10 % of which were of high clinical significance. Importantly, these included 8 synchronous malignancies. The results highlight the wide range of potential IFs, which can be encountered in staging rectal cancer scans, and raise awareness as to their potential clinical relevance and impact on the healthcare system.